Breast Cancer DOI 10.1007/s12282-015-0588-9
SPECIAL FEATURE
Recent advances in sentinel node biopsy for breast cancer
Histological examination of sentinel lymph nodes: significance of macrometastasis, micrometastasis, and isolated tumor cells Hitoshi Tsuda
Received: 5 January 2015 / Accepted: 22 January 2015 Ó The Japanese Breast Cancer Society 2015
Abstract Sentinel lymph node biopsy has been started in 1990 s and has become one of the standard diagnostic procedures used to treat patients with early breast cancer in this century. In Japan, for the microscopic diagnosis of metastasis to sentinel lymph nodes, intraoperative frozen section diagnosis is widely used in combination with subsequent permanent section diagnosis of the residual specimens. Metastatic foci to sentinel lymph nodes have been classified into macrometastasis, micrometastasis, and isolated tumor cells in 2002, and the definition of isolated tumor cells was modified in 2010. Clinical significance of occult sentinel lymph node metastases, being mostly composed of micrometastasis and isolated tumor cells, has been clarified in terms of predictive factors for non-sentinel lymph node metastasis and patient prognosis by large-scale retrospective studies and prospective randomized clinical trials. In the present review, clinical implications of micrometastases and isolated tumor cells in sentinel lymph nodes and the methods for pathological examination of SLN metastases employed in these studies were overviewed. Keywords Sentinel lymph node Micrometastasis Histopathology Isolated tumor cells NSABP B-32 study MIRROR study IBCSG 23-01 study ACOSOG Z0011 study AMAROS study
H. Tsuda (&) Department of Basic Pathology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan e-mail: [email protected]; [email protected]
Introduction The sentinel lymph nodes (SLNs) are lymph nodes where cancer cells in the primary site reach for the first time via regional lymphatic flow [1, 2] Sentinel node biopsy (SLNB) for the diagnosis of regional lymph node metastasis of breast cancer was started in 1993 by Krag DN et al. using radioactive 99mTc-sulfur colloid and in 1994 by Giuliano AF et al. [3, 4] with use of dye lymphazurin. In a large-scale, prospective study, SLNB was shown to be a safe and accurate method of screening the axillary nodes for metastasis and to be associated with reduced arm morbidity and better quality of life than standard axillary treatment. Therefore, SLNB has been recommended as indication for the patients who have early-stage breast cancer with clinically negative nodes [5, 6]. Around the end of 1990 s, SNB was introduced into Japan by pioneer surgeons [7–9]. The Sentinel Node Navigation Surgery Research Group was established in 1999, and SLNB was approved by Pharmaceuticals and Medical Devices Agency (PMDA) in 2010 as routine diagnosis/therapy whose medical fee can be partly reimbursed from social health insurance. In Japan, SLNB has been indicated for the patients with T1-2 breast cancer (mostly 3.0 cm or less on palpation) with clinically negative of axillary lymph node metastasis (cN0) [7–9]. Axillary lymph node dissection (ALND) has been omitted if pathological diagnosis of the SLNs was negative as standard procedure of breast cancer treatment. In contrast, if metastasis was found in a SLN, ALND was added because the probability of metastasis to the ipsilateral axillary lymph nodes other than the SLN (non-SLNs) was estimated to be relatively high. However, clinical significance of the occult metastatic foci in SLNs and/or non-SLNs that were overlooked in routine practice of
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pathology diagnosis remained undetermined. Recently published works appear to provide evidence for the following question: is pathological diagnosis of occult metastases (almost always micrometastases and isolated tumor cells) in SLNs of clinical significance and useful for the treatment of breast cancer? Furthermore, beyond these questions, these studies showed the possibility of omitting ALND in early breast cancer patients with clinically node-negative and SLN-positive diseases when the patients underwent breast-conserving surgery and axillary irradiation.
Classification of SLN metastasis In the International union Against Cancer (UICC) Tumor Lymph Node Metastasis (TNM) Classification of malignant Tumors (2002) and the guidelines by the American Joint Committee on Cancer (AJCC) Staging Manual, 6th edition (2003), SLN metastasis was histopathologically classified into macrometastasis, micrometastasis, and isolated tumor cells (ITCs) [10, 11]. Based on the largest diameter of the largest focus of metastases in the lymph nodes, metastases are classified into macrometastasis (pN1), micrometastasis (pN1mi), and ITCs. Originally, metastasis of [2 mm in diameter was defined pN1, the metastasis between [0.2 mm but 2.0 mm or less was defined as pN1mi, and metastasis of 0.2 mm or less was defined as ITCs. ITCs can be identified by hematoxylin and eosin (HE)-stained sections or immunohistochemistry. Actually, ITCs, described as pN0(i+), are not regarded as metastasis because ITCs do not typically show evidence of metastatic activity (e.g., proliferation or stromal reaction) or penetration of vascular or lymphatic sinus walls [10, 11]. Because of poor reproducibility of the classification in UICC TNM 6th edition and AJCC 2003 [12, 13], the criterion of \200 tumor cells in total was added to the definition of ITCs in AJCC 2010 and UICC/TNM, 7th edition [14, 15] (Table 1). For example, in Fig. 1a, the size of both the larger and the smaller foci of metastases immunoreactive to an anti-cytokeratin antibody was smaller than 0.2 mm, but when the diameter was measured for the
Table 1 Classification of sentinel lymph node metastasis Macrometastasis (pN1)
Metastasis of [2 mm in diameter
Micrometastasis (pN1mi)
Metastasis between [0.2 mm but 2.0 mm or less
Isolated tumor cells pN0(i+)
Metastasis of 0.2 mm or less or of \200 tumor cells in total
ITCs can be identified by hematoxylin and eosin (HE)-stained sections or immunohistochemistry [14, 15]
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Fig. 1 Isolated tumor cells in lymph nodes, detected by immunohistochemistry. a The size of each focus (the larger and the smaller) of metastases immunoreactive to an anti-cytokeratin antibody was smaller than 0.2 mm, but when the diameter was measured as combined area, the largest diameter of the area exceeds 0.2 mm. However, the number of cancer cells is less than 200, from which this case should be classified as ITCs. b A case of sentinel lymph node metastasis of invasive lobular carcinoma. The case is also classified as ITCs
combined area of metastases, the largest diameter of metastases foci exceeds 0.2 mm. However, the number of metastatic cancer cells is less than 200, and this case should be classified as ITCs. Likewise, the case in Fig. 1b is also classified as ITCs. Practice of intraoperative pathological diagnosis of SLN metastasis In the American Society of Clinical Oncology (ASCO) guideline published in 2005, the panel recommended routine ALND for macrometastases or micrometastases found on SLNB. On the other hand, appropriately identified patients with negative results of SLNB need not have completion of ALND. However, the panel also mentioned that
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there were insufficient data to determine whether ALND should be carried out in all cases with micrometastases or ITCs [16]. Therefore, preparation of pathological sections with 200–500 lm interval is described to be optimal. However, too meticulous examination is not realistic in the routine pathology work flow except for those institutes that specialize in breast cancer treatment. In Japan, the routine method of pathological diagnosis of SLN metastasis is not standardized because of difference in the system of pathological diagnosis and the problem of manpower among hospitals. The most prevailing procedure appears to be intraoperative pathological examination composed of cutting each SLN in parallel into 2-mm thick pieces, preparing frozen sections for each piece, fixing them briefly with formalin, and staining with HE. However, because of insufficient manpower, SLNs are often examined after bisection or a single section without cutting. Some institutes adopt preoperative SLNB and subject the biopsied SLNs for permanent sections. In the permanent pathology section, it is easy to dissect formalin-fixed sentinel nodes into 2-mm thick pieces and to visualize subcapsular area. In the Department of Pathology, National Cancer Center Hospital, Tokyo, each SLN was sliced in parallel with shorter axis into 2-mm thick pieces, and each peace was put on nitrocellulose filter to be able to examine sub-capsular area and parenchyma of the SLN, and subjected to frozen sections. In the Department of Pathology, National Defense Medical College, each SLN was sliced in parallel with shorter axis into 2-mm thick pieces, and the method of Kawamoto was also used for visualizing subcapsular area and avoidance of bending or overlapping of a section [17]. With these means, the chances to overlook macrometastasis or micrometastasis may decrease. After intraoperative frozen section diagnosis, the tissue pieces of SLNs are fixed in 10 % formalin and subjected to permanent histopathological diagnosis. In the early in-house studies, the percentage of overlooking metastatic foci in metastasis-positive SLNs in frozen section diagnosis is reported to be 11–43 % in total metastasis-positive SLNs [reviewed in 18]. Exceptionally, Veronesi U et al. achieved an excellently low false-negative rate (5.5 %) in true metastasis-positive lymph nodes by means of exhaustive method: A bisected lymph node along its major axis was subjected to preparation of 4-lm thick frozen sections cut at 50-lm intervals, amounting to around 60 sections per lymph node (30 sections per half lymph node). One section of each pair was stained with HE: if HE was negative or doubtful, the other was stained for cytokeratins using a rapid immunohistochemical method [19]. Intraoperative imprint cytopathological examination (Giemsa stain and/or HE stain) was also reported to be able to accurately identify these metastases [9, 20]. In some hospitals, combined use of HE and IHC
examinations or the use of cytopathological examination is introduced into intraoperative diagnosis. A major problem with cytopathology consists in the difficulty in measuring the diameters of metastatic foci. There are reports that immunohistochemistry using an anti-cytokeratin antibody (e.g., AE1/AE3 or CAM5.2) is useful to identify metastatic foci that were overlooked with HE. Especially, this method is useful to detect metastasis of invasive lobular carcinoma because difficulty in the identification of metastasis foci is well known for invasive lobular carcinoma by intraoperative HE or imprint cytology only [13, 21].
Clinical implication of micrometastasis and ITCs in SLNs In 2001, by employing the ‘‘exhaustive method’’ above, Viale et al. [22] studied 109 patients who had micrometastasis in SLNs and underwent both SNB and complete ALND. The overall frequency of metastasis to non-SLNs was 21.8 %, and the frequency of non-SLN metastases was correlated with the size of the SLN micrometastatic focus: 36.4 % of patients with foci [1 mm whereas only 15.6 % of patients with foci if 1 mm or less. If the diameter of SLN metastasis was [2.0 mm (macrometastasis), 44.7 % of the patients had non-SLN metastasis [22]. Even if SLNs had occult metastases, detected only by immunohistochemistry, 10–15 % of patients had non-SLN metastases by HE [22]. In a meta-analysis by Cserni G et al. [23], around 20 % of patients who were positive of micrometastasis in a SLN showed metastasis in non-SLNs. In contrast, in patients with metastatic foci detectable by immunohistochemistry a SLN only, metastasis in non-SLNs was detected in 9 % [23]. van Deurzen CHM et al. [24] reported in their meta-analysis that overall pooled risk for non-SLN involvement in patients with ITCs in SLNs was 12.3 %. Therefore, results on ITCs in the SLN were somewhat controversial, although ITCs were not regarded as metastases in UICC/TNM classification and AJCC classification. Regarding policies on ALND after the identification of a positive SLN, greater clinical evidence from large clinical trials was waited.
Retrospective studies de Boer et al. [25] performed a retrospective study, named MIRROR (Micrometastases and Isolated Tumor Cells: Relevant and Robust or Rubbish?), to draw evidence concerning micrometastases and prognosis in patients with early breast cancer who received SLNB using nationwide data of the Netherlands Cancer Registry. Their study
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randomly included 856 women with node-negative disease who did not receive systemic adjuvant therapy, other 856 women with ITCs or micrometastases who did not receive adjuvant therapy, and 994 women with ITCs or micrometastases who received adjuvant therapy. All these three cohorts contained patients who received both types of surgery (breast-conserving surgery in 71.0 % and mastectomy in 29.0 % in total) and patients with ALND (49.4 % in total) and without (50.6 % in total). In pathological review in their study, handling of lymph nodes was as follows: SLNs were examined for widely spaced step sections (at minimum 3 sections cut at least at 150-lm intervals). These sections were stained with HE, and immunohistochemistry was added in HE-negative cases. For non-SLNs, 2- to 5-mm interval sections were made and stained with HE only. By the comparison of patient prognosis between the 856 patients of the node-negative, no-adjuvant therapy cohort and the 856 patients of node-positive (micrometastasis or ITCs), no-adjuvant therapy cohort, the unadjusted 5-year disease-free survival (DFS) rate in the latter cohort was significantly reduced (nearly 10 %) as compared with that in the former cohort (76.5 vs 85.7 %, P \ 0.001) [25]. Among the 856 patients with micrometastasis or ITCs, the unadjusted 5-year DFS rate was similar between the patient subset with ITCs and the patient subset with micrometastases (77.2 and 75.9 %, respectively; P = 0.77). Among patients with ITCs or micrometastases, the unadjusted 5-year DFS rate in the node-positive, no-adjuvant-therapy cohort subset was significantly reduced (nearly 10 %) as compared with that rate in the nodepositive, adjuvant-therapy cohort subset (76.5 and 86.2 %, P \ 0.001). Among the patients with ITCs only, the patient subset that did not receive adjuvant therapy had a significantly reduced 5-year DFS rate as compared with patient cohort that received adjuvant therapy (77.2 and 83.0 %, P = 0.04). Among patients with micrometastases, the patient cohort that did not receive adjuvant therapy had a significantly reduced 5-year DFS rate as compared with the patient cohort that received adjuvant therapy (75.9 and 87.9 %, P \ 0.001) [25]. From these results, they concluded that DFS was improved by adjuvant systemic therapy in patients with ITCs or micrometastases. In the study of de Boer et al. [26], central pathology review was adopted for the purpose of quality control of nodal breast cancer staging. The discrepancy between the local pathologists and review pathologists was high resulting in 24 % changes of the final pN status (kappa coefficient of 0.69). The 5-year DFS was better for all subgroups considering the classification as assessed by the review pathologists. de Boer et al. [27] also conducted a systematic review of prognostic relevance of micrometastases and ITCs in lymph nodes from patients with breast cancer and concluded that the presence (vs the absence) of metastases of
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2 mm or less in diameter in axillary lymph nodes detected on single-section examination was associated with poorer DFS and overall survival (OS). Another study showed different results. Using a cohort of 790 patients in the John Wayne Cancer Institute, Santa Monica, CA, between 1992 and 1999, Hansen NM et al. [28] examined the effect of micrometastasis on patients’ clinical outcome. In their study, [90 % the patients with macrometastasis, micrometastasis, and ITCs received adjuvant systemic therapies (91, 96, and 93 %, respectively) and 66 % of patients of pN0 group also received adjuvant systemic therapies. Pathological review was performed as follows: each SLN was bisected and blocked, prepared for permanent sectioning, and stained with HE. If negative, 6–8 sections of the SLN were submitted for immunohistochemistry using a monoclonal antibody against cytokeratins [28]. At a median follow-up of 72.5 months the size of SLN metastases was a significant predictor of DFS and OS. There was no statistically significant difference in 8-year DFS and 8-year OS among the patient groups with micrometastasis (92.05 and 94.11 %), with ITCs (97.57 and 100 %), and with pN0 (95.86 and 96.85 %) [27]. In contrast, there was a significant difference in 8-year DFS and 8-year OS for macrometastasis group (82.50 and 88.40 %) (P \ 0.0001 and P \ 0.001) [28].
Prospective studies The incidence of the metastases that are overlooked in routine pathological examinations, that is, ‘‘occult metastases’’, is reported to be 9 to 30 %, and most of these occult metastases are micrometastases or ITCs. In 2011–2013, the results of three prospective randomized studies relevant to SLN metastasis were published in the National Surgical Adjuvant Breast and Bowel Project (NSABP) trial B-32, the International Breast Cancer Study Group (IBCSG) trial 23-01, and the American College of Surgeons Oncology Group (ACOSOG) trial Z0011 [29–31]. The NSABP B-32 trial aimed to determine whether SLN resection in breast cancer patients achieved the same survival and regional control as axillary dissection but with fewer side effects [29]. 5,611 women with invasive breast cancer were randomly assigned to SLN resection plus ALND (Group 1) or to SLN resection alone with ALNB only if SLNs were positive (Group 2). Because planned surgical treatment was randomized within each participating institution, the percentage of lumpectomy (87.7 and 87.0 %) and mastectomy (12.3 and 13.0 %) was almost equal between SLN resection plus ALND group and SLN resection-only group. The use of systemic adjuvant therapy and radiation therapy was also well balanced: 85 % of Group 1 and 84.1 % of Group 2 patients received systemic
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adjuvant therapy and 82.3 % of Group 1 and 82.2 % of Group 2 patients received radiation therapy. SLNs from both Groups 1 and 2 were evaluated postoperatively with routine stains at approximately 2-mm intervals through the node. Immunohistochemistry was not permitted except for confirmation of suspicious findings on routine HE stains [29]. Among the 3,986 SLN-negative women with follow-up information, 8-year OS of Group 1 and 2 was 91.8 and 90.3 %, respectively (P = 0.12), and 8-year DFS of Group 1 and 2 was 82.4 and 81.5 %, respectively (P = 0.54). Regional node recurrence rates between Groups 1 and 2 did not differ significantly (P = 0.22) [29]. NSABP B-32 also studied clinical significance of occult metastasis in SLNs [32]. This trial examined whether patients with initially negative SLNs who have occult metastases detected on deeper levels and cytokeratin immunohistochemistry stains are a risk for regional or distant metastases. Tissue blocks of the SLNs obtained from all pN0 patients by the participating site were subjected to the central institute for the evaluation of occult metastases. One HE section and one cytokeratin immunohistochemistry section were evaluated at two levels—approximately 0.5 mm and 1.0 mm—deeper into the paraffin block (four sections total). This two-level, widely spaced protocol was designed to exclude micrometastases larger than 1.0 mm from the ‘‘occult metastases negative’’ group (Fig. 1) [33]. In 3,884 routinely pN0 patients with follow-up data, occult metastases were detected in 616 (15.9 %), 11.1 % being ITC clusters, 4.4 % micrometastases, and 0.4 % macrometastases. Therefore, most of the occult metastases were ITCs or micrometastases [32]. In these routine pN0 patients, the detection of occult metastasis was a significant risk factor: 5-year regional recurrence rate in 616 pN0 patients with occult metastases was 1.1 %, and the rate in 300 pN0 patients with occult metastases who underwent SLNB without ALND was 1.7 %. In contrast, 5-year regional recurrence rate in 3,268 pN0 patients without occult metastases was 0.4 %, and the rate in 1660 pN0 patients with occult metastases who underwent SLNB without ALND was 0.5 %. Likewise, in pN0 patients who underwent SLNB without ALND, there was a significant difference in OS, DFS, and distant DFS between patients with occult metastases and those without [32, 33]. The authors concluded that, however, difference in outcome at 5 years was small between these two groups [31, 32]. These data do not indicate a clinical benefit of additional evaluation, including immunohistochemical analysis, of initially negative SLNs in patients with breast cancer [29]. Systemic adjuvant therapy was more often administered in the patient group with occult metastases, and it was hypothesized that without systemic adjuvant
therapy the difference in adverse outcome might nave been be larger [32]. The IBCSG 23-01 was a phase III study that randomized those patients with micrometastasis or ITCs in the SLNs, based on HE pathology examination, to ALND or no ALND, to assess (like ACOSOG Z0011) the impact of avoiding ALND on long-term patient outcomes [30]. In that study, enrollment was limited to patients with micrometastases or ITCs, and 95.6 % of patients had only one positive SLN limited to ITCs or micrometastases. Breast conservation surgery with radiation was performed for 88.4 % of the enrolled patients and 96 % of patients received systemic therapy. In the IBCSG 23-01, all SLNs were entirely sectioned at 50–200 lm intervals, and each section (frozen or permanent) was examined by HE. Cytokeratin immunostaining was used only when the presence of micrometastasis was suspected, but not certain, or not determined, on HE sections. That study was conducted in a time frame in which surgeons were already adapting their practices and decreasing their performance of ALND for micrometastatic SLN disease, and closed early after meeting less than 50 % of its targeted accrual goal [30, 34]. Regional recurrence rates and DFS rates (1 % vs 87.8 %, respectively) of the no-ALND group were not different from those (0.2 % and 84.4 %, respectively) of the ALND group after a 5-year median follow-up, and ALND might be avoided safely in the patients with early breast cancer (\3 cm tumor) with ITCs or micrometastases, receiving breast conservation surgery with radiation, and adjuvant systemic therapy [30, 34]. The common conclusion from NSABP B-32 and IBCSG 23-01 was that, compared with SLNB alone, completion of ALND does not appear to improve outcomes for breast cancer patients with microscopic nodal metastases. A larger impact in practice of axillary management in breast cancer patients was derived from the result of the ACOSOG Z0011 trial. This study was designed as a phase III non-inferiority trial to determine whether completion of ALND for breast cancer patients with SLN metastasis, undergoing breast conservation surgery and adjuvant whole-breast irradiation, affects overall survival [31]. Eligibility criteria included patients with cT1-2, cN0 invasive breast cancer, and one or two SLN metastasis without extranodal extension detected by frozen section, imprint cytology or HE staining on permanent section. Patients with breast cancer to the SLN identified by immunohistochemistry were not eligible. Not only patients with micrometastases but also those with macrometastases to SLNs were included. All patients received breast conservation surgery and SLNB, with histologically negative margins of the lumpectomy specimen. Patients with metastasis in one
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to two SLNs were randomly assigned into ALND or noALND groups. Whole-breast irradiation was administered after surgery via two tangential fields. More than 90 % of patients received systemic therapy [31, 34, 35]. Similar to the IBCSG 23-01 study, the Z0011 study was also closed early after meeting less than 50 % of its targeted accrual goal. The ACOSOC Z0011 allowed micrometastatic or macrometastatic disease in the SLNs, different from the IBCSG 23-01 study that limited enrollment to patients with micrometastases or ITCs. In ACOSOG Z0011 study, 50 % of patients (430 of 856) had macrometastatic disease, 35 % (301 of 856) had micrometastases, and the remainder no or unknown extent of nodal disease [31, 34]. In addition, in the Z0011 study, 79 % (324 of 415) of the SLN only group had zero or one metastasis-positive SLN, whereas in the IBCSG study, 95 % of patients had only one metastasispositive SLN. Therefore, nodal burden was higher in the ACOSOG Z0011 study than in the IBCSG 23-01 [35]. At a median follow-up of 6.3 years, the use of SLN dissection alone compared with ALND did not appear to result in statistically inferior survival (P = 0.008 for noninferiority). The 5-year OS rates were 92.5 % in the SLN dissection-alone group and 91.8 % in the ALND group (P = 0.25). The 5-year DFS rates were 83.9 % for the SLN dissection-alone group and 82.2 % for the ALND group (P = 0.14) [31]. The 5-year total locoregional recurrence rate in the SLN dissection-alone group was 2.5 % compared with 3.6 % in the ALND group. Therefore, it was indicated that the addition of ALND does not benefit in terms of local control, DFS, or OS to the patients with clinical T1-2 tumors and a positive SLN metastasis who underwent breast-conserving therapy followed by systemic therapy [31]. With the results of previous studies that support the omission of ALND, the Z0011 study results were incorporated in clinical practice guidelines [36, 37]. In these guidelines, it is described that clinicians should not recommend ALND for women with early-stage breast cancer and one or two SLN metastases who will undergo breast conservation surgery with conventionally fractionated whole-breast radiotherapy. It is also recommended that the clinician may offer ALND for women with early-stage breast cancer with nodal metastases found on SLNB who will undergo mastectomy [37]. The European Organization for Research and Treatment of Cancer (EORTC) 10981-22023 AMAROS (the After Mapping of the Axilla: Radiotherapy or Surgery) trial is a randomized, multicenter, phase III non-inferiority trial in patients with T1-2 primary, unifocal, invasive breast cancer, with no palpable lymphadenopathy to investigate as to whether breast cancer patients with a tumor-positive SLN are best treated with an ALND or axillary radiotherapy
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[38]. Before the SLNB procedure, patients were randomized between ALND and axillary radiotherapy. Pathological SLN examination in the AMAROS protocol was as follows: As a minimal requirement, three histological levels (500-lm distance) for each SLN were examined. On each level, two parallel sections were performed, one for immunohistochemistry for cytokeratins and one for HE. Immunohistochemical staining was required only when HE staining was negative. The SLN was considered tumor-positive if any tumor deposit in the node or in the afferent or efferent lymph vessels was found. Tumor deposits were categorized as ITCs, micrometastases, or macrometastases according to UICC/TNM classification, 6th edition. After protocol amendment in 2008, SLNs with only ITCs were no longer regarded as SLN positive [38, 39]. Local treatment of the breast consisted of breast-conserving therapy including whole-breast radiotherapy or mastectomy with or without irradiation of the chest wall. Adjuvant axillary radiotherapy after ALND was allowed when at least 4 positive nodes were found. The use of adjuvant systemic treatment was at the discretion of treating multidisciplinary team. The primary endpoint in the group of SLN-positive patients was 5-year axillary recurrence. Among the SLNpositive patient group, breast-conserving surgery was performed for 82 % in both the ALND subgroup (n = 744) and the axillary radiotherapy subgroup (n = 681), and mastectomy was performed for 17 and 18 % of these subgroups, respectively. The number of positive SLNs was 1 or 2 in 95 % of both the ALND subgroup and the axillary radiotherapy subgroup, and the largest SLN metastases in the ALND subgroup and axillary radiotherapy subgroup were macrometastasis in 59 and 62 %, micrometastasis in 29 and 29 %, and ITCs in 12 and 10 %, respectively [38]. Systemic adjuvant therapy was administered for 90 % of the patients in both subgroups. The interim report of the AMAROS study assessed the further nodal involvement in macromeastases, micrometastases, and ITCs, separately, in the SLN-positive ALND group [39]: Further nodal involvement was seen in 41, 18, and 18 % of the patients with macrometastases, micrometastases, and ITCs, respectively, and extensive nodal involvement (4 or more) was slightly higher in patients with micrometastases (6 %) than in ITCs (3 %). In the patients with positive SLNs, with median followup period of 6.1 years, 5-year axillary recurrence was 0.43 % after ALND versus 1.19 % after axillary radiotherapy. There were no significant differences in DFS and OS between these treatment groups: 5-year DFS and OS were 86.9 and 93.3 % in the ALND group and 82.7 and 92.5 % in the axillary radiotherapy group and the axillary radiotherapy group, respectively. The axillary radiotherapy
Breast Cancer b Fig. 2 A schematic presentation of the methods for pathological SLN
A 150 µm 150 µm
B 2 mm 2 mm 2 mm
C
0.5 mm 1.0 mm 0.5 mm 1.0 mm
D 50
200 µm
E 500 µm 500 µm
seemed to be non-inferior to ALND in the population of patients with clinically node negative axilla and a positive SLN. The AMAROS study cannot answer the remaining question of which subset of clinically node-negative, SLNpositive patients still require axillary treatments. Nonetheless, if further axillary treatment is needed in clinically node-negative, SLN-positive patients, axillary radiotherapy could be chosen instead of ALND [38].
Discussion Internationally, there is no consensus on the pathology protocol to be used to examine the SLN in breast cancer patients except that a node should be cut no thicker than 2 mm [37, 40]. The methods for pathological SLN examination employed in the major protocol studies are schematically presented in Fig. 2, according to the description in the journals. Histological examination was performed at three levels on an average except for the IBCSG 23-01 and part of occult metastasis study in the NASBP B-32 [25, 29–32].
examination employed in the protocol studies. A. MIRROR trial [25]. SLNs were examined for widely spaced step sections (at minimum 3 sections cut at least at 150-lm intervals). The sections were stained with HE, and immunohistochemistry was added in HE-negative cases. For non-SLNs, 2- to 5-mm interval sections were made and stained with HE only. B. NSABP B-32 trial [29]. SLNs were evaluated postoperatively with routine stains at approximately 2-mm intervals through the node. Immunohistochemistry was not permitted except for confirmation of suspicious findings on routine HE stains. C. NSABP B-32 trial for detection of occult micrometastases and isolated tumor cells [32]. Tissue blocks of the SLNs obtained from all pN0 patients by the participating site were subjected to the central institute for the evaluation of occult metastases. One HE and cytokeratin immunohistochemical stained section was evaluated at two levels—approximately 0.5 mm and 1.0 mm—deeper into the paraffin block (four sections total). This two-level, widely spaced protocol was designed to exclude micrometastases larger than 1.0 mm from the ‘‘occult metastases negative’’ group. D. IBCSG 23-01 trial [30]. All SLNs were entirely sectioned at 50–200 lm intervals and each section (frozen or permanent) was examined by HE staining. Cytokeratin immunostaining was used only when the presence of micrometastasis was suspected but not certain, or not determiner, on HE sections. E. AMAROS trial [38]. As a minimal requirement, three histological levels (500 lm distance) for each SLN were examined. On each level, two parallel sections were performed, one for immunohistochemistry for cytokeratins and one for HE. Immunohistochemical staining was required only when HE staining was negative
From the results of these studies, not only macrometastasis but also micrometastases or ITCs in SLNs are accompanied relatively frequently by non-SLN metastases [25, 29–32]. In a retrospective study, micrometastases and ITCs in SLNs were certainly indicators for worse clinical outcome of breast cancer patients when systemic adjuvant therapy was not undergone [25]. In prospective randomized studies, the impact of micrometastases and ITCs on patients’ clinical outcome was not large even if differences in the rates of locoregional recurrence, DFS, and/or OS were statistically significant [29, 30]. In these prospective studies, most of the patients who were entered in the arm of SLNB only without ALND received breast-conserving therapies, most of which included lumpectomy and whole-breast irradiation, and systemic adjuvant therapies. Therefore, it was highly probable that the residual non-SLN metastases in these patients disappeared by these therapies, which caused decrease in the rates of regional recurrence, DFS, and OS. With regard to the results in the retrospective study by Hansen NM et al. [28], similar interpretation was possible. At present, there are no data about the clinical implication of SLN micrometastases/ITCs in cN0 breast cancer patients who received mastectomy without axillary irradiation. Interobserver inconsistency in the diagnosis of small foci of SLN metastases is shown by several protocol studies. Such inconsistency may derive from the ambiguity with the classification and lack in consensus acquisition among
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pathologists prior to the study [12, 40]. For providing standardized pathology criteria and definition, the incorporation of the number of metastatic cancer cells as well as the largest diameter of metastatic foci will be important [13]. Turner RR et al. [12] stated that training program using illustrative examples with electronic archives would be helpful for the improvement of interobserver agreement in the diagnosis of small SLN metastasis. Central pathology review might contribute to quality assurance of nodal breast cancer staging in protocol studies [26]. We are able to learn much about how large-scale protocol studies incorporate pathology practice. In Japan, one of the issues involves evidence acquisition about one-step nucleic acid amplification (OSNA) method that is introduced for intraoperative SLN diagnosis [41–43]. An OSNA-positive SLN is categorized as pN0(mol?) in UICC/TNM classification, 7th edition [14, 15]. However, the concept of development of OSNA is largely the decrease in the burden of pathology practice. In most institutes introducing OSNA method, the entire SLNs are used up for this assay, and no tissue blocks remain for permanent pathology diagnosis. To establish state-of-the- art surgical axillary management using OSNA, large-scale clinical trials of OSNA version and clarification of concordance between SLN diagnoses by OSNA and by pathology might be required. In conclusion, clinical implication of micrometastases and ITCs has been clarified by multiple large-scale retrospective and prospective studies. Although pathological detection of micrometastases and ITCs in the SLNs are indicators of worse clinical outcome of patients with clinically node-negative breast cancer, such negative effects appeared to be much decreased by systemic adjuvant therapy and irradiation in case of breast-conserving therapy. A similar effect would operate in the patients with breast cancer with macrometastases to 1–2 SLNs who received systemic adjuvant therapy and breast-conserving therapy with irradiation. For the assurance of quality in clinical trials, consensus on the protocol for pathological examination of SLNs and standardization of pathological classification of SLN metastasis would be important. Acknowledgments This work was supported in part by the National Cancer Center Research and Development Fund and from the Grandin-Aid of the Ministry of Health, Labor, and Welfare, Japan. Conflict of interest interest.
The author declares that there is no conflict of
References 1. Cavanas R. An approach for the treatment of penile carcinoma. Cancer. 1977;39:456–66.
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2. Morton DL, Wen DR, Wong JH, Economou JS, Cagle LA, Storm FK, et al. Technical details of intraoperative lymphatic mapping for early stage melanoma. Arch Surg. 1992;127:392–9. 3. Krag DN, Weaver DL, Alex JC, Fairbank JT. Surgical resection and radio-localization of the sentinel node in breast cancer using a gamma probe. Surg Oncol. 1993;2:335–40. 4. Giuliano AE, Kirgan DM, Guenther JM, Morton DL. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg. 1994;220:391–401. 5. Veronesi U, Paganelli G, Viale G, Luini A, Zurrida S, Galimberti V, et al. A randomized comparison of sentinel-node biopsy with routine axillary dissection in breast cancer. N Engl J Med. 2003;349:546–53. 6. Mansel RE, Fallowfield L, Kissin M, Goyal A, Newcombe RG, Dixon JM, et al. Randomized multicenter trial of sentinel node biopsy versus standard axillary treatment in operable breast cancer: the ALMANAC Trial. J Natl Cancer Inst. 2006;98:599–609. 7. Noguchi M, Tsugawa K, Bando E, Kawahara F, Miwa K, Yokoyama K, et al. Sentinel lymphadenectomy in breast cancer: identification of sentinel lymph node and detection of metastases. Breast Cancer Res Treat. 1999;53:97–104. 8. Sato K, Hiraide H, Uematsu M, Tamaki K, Ishikawa H, Yamasaki T, et al. Efficacy and significance of sentinel lymph node identification with technetium-99m-labeled tin colloids for breast cancer. Breast Cancer. 1998;5:389–93. 9. Motomura K, Inaji H, Komoike Y, Kasugai T, Nagumo S, Noguchi S, et al. Sentinel node biopsy in breast cancer patients with clinically negative lymph nodes. Breast Cancer. 1999;6:259–62. 10. Sobin LH, Wittekind C. TNM classification of malignant tumours. International Union against Cancer. 6th ed. New York: Wiley-Liss; 2002. 11. Singletary SE, Allred C, Ashley P, Bassett LW, Berry D, Bland KI, et al. Revision of the American Joint Committee on Cancer staging system for breast cancer. J Clin Oncol. 2002;20:3628–36. 12. Turner RR, Weaver DL, Cserni G, Lester SC, Hirsch K, Elaschoff DA, et al. Nodal stage classification for breast carcinoma: improving interobserver reproducibility through standardized histologic criteria and image-based training. J Clin Oncol. 2008;26:258–63. 13. Apple SK, Moatamed NA, Finck RH, Sullivan PS. Accurate classification of sentinel lymph node metastases in patients with lobular breast carcinoma. Breast. 2010;19:360–4. 14. Sobin L, Gospodarowicz M, Wittekind C. TNM Classification of malignant Tumours. International Union Against Cancer. 7th ed. Chichester: Wiley; 2010. 15. Edge SB, Byrd DR, Compton CC, Fritz AG, Greene FL, Trotti A. AJCC Cancer Staging Manual. 7th ed. New York: Springer; 2010. 16. Lyman GH, Giuliano AE, Somerfield MR, Benson AB III, Bodurka DC, Burstein HJ, et al. American Society of Clinical Oncology. American Society of Clinical Oncology guideline recommendations for sentinel lymph node biopsy in early-stage breast cancer. J Clin Oncol. 2005;23:7703–20. 17. Kawamoto T. Use of a new adhesive film for the preparation of multi-purpose fresh-frozen sections from hard tissues, wholeanimals, insects and plants. Arch Histol Cytol. 2003;66:123–43. 18. Chao C, Wong SL, Ackermann D, Simpson D, Carter MB, Brown CM, et al. Utility of intraoperative frozen section analysis of sentinel lymph nodes in breast cancer. Am J Surg. 2001;182:609–15. 19. Veronesi U, Paganelli G, Viale G, Galimberti V, Luini A, Zurrida S, et al. Sentinel lymph node biopsy and axillary dissection in breast cancer: results in a large series. J Natl Cancer Inst. 1999;91:368–73. 20. Aihara T, Munakata S, Morino H, Takatsuka Y. Comparison of frozen section and touch imprint cytology for evaluation of sentinel lymph node metastasis in breast cancer. Ann Surg Oncol. 2004;11:419–22.
Breast Cancer 21. Taras AR, Hendrickson NA, Pugliese MS, Lowe KA, Atwood M, Beatty JD. Intraoperative evaluation of sentinel lymph nodes in invasive lobular carcinoma of the breast. Am J Surg. 2009;197:643–7. 22. Viale G, Maiorano E, Mazzarol G, Zurrida S, Galimberti V, Luini A, et al. Histologic detection and clinical implications of micrometastases in axillary sentinel lymph nodes for patients with breast carcinoma. Cancer. 2001;92:1378–84. 23. Cserni G, Gregori D, Merletti F, Sapino A, Mano MP, Ponti A, et al. Meta-analysis of non-sentinel node metastases associated with micrometastatic sentinel nodes in breast cancer. Br J Surg. 2004;91:1245–52. 24. van Deurzen CHM, de Boer M, Monninkhof EM, Bult P, van der Wall E, Tjan-Heijnen VCG, et al. Non-sentinel lymph node metastases associated with isolated breast cancer cells in the sentinel node. J Natl Cancer Inst. 2008;100:1574–80. 25. de Boer M, van Deurzen CHM, van Dijck JAAM, Borm GF, van Diest PJ, Adang EMM, et al. Micrometastases or isolated tumor cells and the outcome of breast cancer. N Engl J Med. 2009;361:653–63. 26. Vestjens JHMJ, Pepels MJ, de Boer M, Borm GF, van Deurzen CHM, van Diest PJ, et al. Relevant impact of central pathology review on nodal classification in individual breast cancer patients. Ann Oncol. 2012;23:2561–6. 27. de Boer M, van Dijck JA, Bult P, Borm GF, Tjan-Heijnen VC. Breast cancer prognosis and occult lymph node metastases, isolated tumor cells, and micrometastases. J Natl Cancer Inst. 2010;102:410–25. 28. Hansen NM, Grube B, Ye X, Turner RR, Brenner RJ, Sim MS, et al. Impact of micrometastases in the sentinel node of patients with invasive breast cancer. J Clin Oncol. 2009;27:4679–84. 29. Krag DN, Anderson SJ, Julian TB, Brown AM, Harlow SP, Costantino JP, et al. Sentinel-lymph-node resection compared with conventional axillary-lymph-node dissection in clinically node-negative patients with breast cancer: overall survival findings from the NSABP B-32 randomised phase 3 trial. Lancet Oncol. 2010;11:927–33. 30. Galimberti V, Cole BF, Zurrida S, Viale G, Luini A, Veronesi P, et al. International Breast Cancer Study Group Trial 23-01 investigators. Axillary dissection versus no axillary dissection in patients with sentinel-node micrometastases (IBCSG 23-01): a phase 3 randomised controlled trial. Lancet Oncol. 2013;14:297305. Erratum in: Lancet Oncol. 2013;14:e254. 31. Giuliano AE, Hunt KK, Ballman KV, Beitsch PD, Whitworth PW, Blumencranz PW, et al. Axillary dissection vs no axillary dissection in women with invasive breast cancer and sentinel node metastasis. A randomizes clinical trial. JAMA. 2011;305:569–75. 32. Weaver DL, Ashikaga T, Krag DN, Skelly JM, Anderson SJ, Harlow SP, et al. Effect of occult metastases on survival in nodenegative breast cancer. N Engl J Med. 2011;364:412–21.
33. Weaver DL, Le UP, Dupuis SL, Weaver KAE, Harlow SP, Ashikaga T, et al. Metastasis detection in sentinel lymph nodes: comparison of a limited widely spaced (NSABP protocol B-32) and a comprehensive narrowly spaced paraffin block sectioning strategy. Am J Surg Pathol. 2009;33:1583–9. 34. Hieken TJ, Boughey JC. Axillary dissection versus no axillary dissection in patients with sentinel-node micrometastases: commentary on the IBCSG 23-01 Trial. Gland Surg. 2013;2:128–32. 35. Gatzemeier W, Mann GB. Which sentinel lymph-node (SLN) positive breast cancer patient needs an axillary lymph-node dissection (ALND)—ACOSOG Z0011 results and beyond. Breast. 2013;22:211–6. 36. Gradishar WJ, Anderson BO, Blair SL, Burstein HL, Cyr A, Elias AD, et al. NCCN breast cancer version 3. Clinical practice guidelines in oncology. J Natl Compr Cancer Netw. 2014;2014(12):542–90. 37. Lyman GH, Temin S, Edge SB, Newman LA, Turner RR, Weaver DL, et al. Sentinel lymph node biopsy for patients with early-stage breast cancer: American Society of Clinical Oncology. American Society of Clinical Oncology practice guideline update. J Clin Oncol. 2014;32:1365–83. 38. Donker M, van Tienhoven G, Straver ME, Meijnen P, van de Velde CJ, Mansel RE, et al. Radiotherapy or surgery of the axilla after a positive sentinel node in breast cancer (EORTC 10981-22023 AMAROS): a randomised, multicentre, open-label, phase 3 non-inferiority trial. Lancet Oncol. 2014;15:1303–10. 39. Straver ME, Meijnen P, van Tienhoven G, van de Velde CJ, Mansel RE, Bogaerts J, et al. Sentinel node identification rate and nodal involvement in the EORTC 10981-22023 AMAROS trial. Ann Surg Oncol. 2010;17:1854–61. 40. Bolster MJ, Pepels MJ, Wauters CAP, Schapers RFM, Meijer JWR, Strobbe LJA, et al. Is the sentinel lymph node pathology protocol in breast cancer patients associated with the risk of regional recurrence? Eur J Surg Oncol. 2013;39:437–41. 41. Tsujimoto M, Nakabayashi K, Yoshidome K, Kaneko T, Iwase T, Akiyama F, et al. One-step nucleic acid amplification for intraoperative detection of lymph node metastasis in breast cancer patients. Clin Cancer Res. 2007;13:4807–16. 42. Tamaki Y, Akiyama F, Iwase T, Kaneko T, Tsuda H, Sato K, et al. Molecular detection of lymph node metastases in breast cancer patients: results of a multi-center trial using the one-step nucleic acid amplification (OSNA) assay. Clin Cancer Res. 2009;15:2879–84. 43. Jimbo K, Kinoshita T, Suzuki J, Asaga S, Hojo T, Yoshida M, et al. Combination use of one-step nucleic acid amplification and conventional histological examination for intraoperative diagnosis of sentinel lymph node metastasis in patients with early breast cancer. Breast. 2013;22:1194–9.
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SPECIAL FEATURE
Recent advances in sentinel node biopsy for breast cancer
Histological examination of sentinel lymph nodes: significance of macrometastasis, micrometastasis, and isolated tumor cells Hitoshi Tsuda
Received: 5 January 2015 / Accepted: 22 January 2015 Ó The Japanese Breast Cancer Society 2015
Abstract Sentinel lymph node biopsy has been started in 1990 s and has become one of the standard diagnostic procedures used to treat patients with early breast cancer in this century. In Japan, for the microscopic diagnosis of metastasis to sentinel lymph nodes, intraoperative frozen section diagnosis is widely used in combination with subsequent permanent section diagnosis of the residual specimens. Metastatic foci to sentinel lymph nodes have been classified into macrometastasis, micrometastasis, and isolated tumor cells in 2002, and the definition of isolated tumor cells was modified in 2010. Clinical significance of occult sentinel lymph node metastases, being mostly composed of micrometastasis and isolated tumor cells, has been clarified in terms of predictive factors for non-sentinel lymph node metastasis and patient prognosis by large-scale retrospective studies and prospective randomized clinical trials. In the present review, clinical implications of micrometastases and isolated tumor cells in sentinel lymph nodes and the methods for pathological examination of SLN metastases employed in these studies were overviewed. Keywords Sentinel lymph node Micrometastasis Histopathology Isolated tumor cells NSABP B-32 study MIRROR study IBCSG 23-01 study ACOSOG Z0011 study AMAROS study
H. Tsuda (&) Department of Basic Pathology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-8513, Japan e-mail: [email protected]; [email protected]
Introduction The sentinel lymph nodes (SLNs) are lymph nodes where cancer cells in the primary site reach for the first time via regional lymphatic flow [1, 2] Sentinel node biopsy (SLNB) for the diagnosis of regional lymph node metastasis of breast cancer was started in 1993 by Krag DN et al. using radioactive 99mTc-sulfur colloid and in 1994 by Giuliano AF et al. [3, 4] with use of dye lymphazurin. In a large-scale, prospective study, SLNB was shown to be a safe and accurate method of screening the axillary nodes for metastasis and to be associated with reduced arm morbidity and better quality of life than standard axillary treatment. Therefore, SLNB has been recommended as indication for the patients who have early-stage breast cancer with clinically negative nodes [5, 6]. Around the end of 1990 s, SNB was introduced into Japan by pioneer surgeons [7–9]. The Sentinel Node Navigation Surgery Research Group was established in 1999, and SLNB was approved by Pharmaceuticals and Medical Devices Agency (PMDA) in 2010 as routine diagnosis/therapy whose medical fee can be partly reimbursed from social health insurance. In Japan, SLNB has been indicated for the patients with T1-2 breast cancer (mostly 3.0 cm or less on palpation) with clinically negative of axillary lymph node metastasis (cN0) [7–9]. Axillary lymph node dissection (ALND) has been omitted if pathological diagnosis of the SLNs was negative as standard procedure of breast cancer treatment. In contrast, if metastasis was found in a SLN, ALND was added because the probability of metastasis to the ipsilateral axillary lymph nodes other than the SLN (non-SLNs) was estimated to be relatively high. However, clinical significance of the occult metastatic foci in SLNs and/or non-SLNs that were overlooked in routine practice of
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pathology diagnosis remained undetermined. Recently published works appear to provide evidence for the following question: is pathological diagnosis of occult metastases (almost always micrometastases and isolated tumor cells) in SLNs of clinical significance and useful for the treatment of breast cancer? Furthermore, beyond these questions, these studies showed the possibility of omitting ALND in early breast cancer patients with clinically node-negative and SLN-positive diseases when the patients underwent breast-conserving surgery and axillary irradiation.
Classification of SLN metastasis In the International union Against Cancer (UICC) Tumor Lymph Node Metastasis (TNM) Classification of malignant Tumors (2002) and the guidelines by the American Joint Committee on Cancer (AJCC) Staging Manual, 6th edition (2003), SLN metastasis was histopathologically classified into macrometastasis, micrometastasis, and isolated tumor cells (ITCs) [10, 11]. Based on the largest diameter of the largest focus of metastases in the lymph nodes, metastases are classified into macrometastasis (pN1), micrometastasis (pN1mi), and ITCs. Originally, metastasis of [2 mm in diameter was defined pN1, the metastasis between [0.2 mm but 2.0 mm or less was defined as pN1mi, and metastasis of 0.2 mm or less was defined as ITCs. ITCs can be identified by hematoxylin and eosin (HE)-stained sections or immunohistochemistry. Actually, ITCs, described as pN0(i+), are not regarded as metastasis because ITCs do not typically show evidence of metastatic activity (e.g., proliferation or stromal reaction) or penetration of vascular or lymphatic sinus walls [10, 11]. Because of poor reproducibility of the classification in UICC TNM 6th edition and AJCC 2003 [12, 13], the criterion of \200 tumor cells in total was added to the definition of ITCs in AJCC 2010 and UICC/TNM, 7th edition [14, 15] (Table 1). For example, in Fig. 1a, the size of both the larger and the smaller foci of metastases immunoreactive to an anti-cytokeratin antibody was smaller than 0.2 mm, but when the diameter was measured for the
Table 1 Classification of sentinel lymph node metastasis Macrometastasis (pN1)
Metastasis of [2 mm in diameter
Micrometastasis (pN1mi)
Metastasis between [0.2 mm but 2.0 mm or less
Isolated tumor cells pN0(i+)
Metastasis of 0.2 mm or less or of \200 tumor cells in total
ITCs can be identified by hematoxylin and eosin (HE)-stained sections or immunohistochemistry [14, 15]
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Fig. 1 Isolated tumor cells in lymph nodes, detected by immunohistochemistry. a The size of each focus (the larger and the smaller) of metastases immunoreactive to an anti-cytokeratin antibody was smaller than 0.2 mm, but when the diameter was measured as combined area, the largest diameter of the area exceeds 0.2 mm. However, the number of cancer cells is less than 200, from which this case should be classified as ITCs. b A case of sentinel lymph node metastasis of invasive lobular carcinoma. The case is also classified as ITCs
combined area of metastases, the largest diameter of metastases foci exceeds 0.2 mm. However, the number of metastatic cancer cells is less than 200, and this case should be classified as ITCs. Likewise, the case in Fig. 1b is also classified as ITCs. Practice of intraoperative pathological diagnosis of SLN metastasis In the American Society of Clinical Oncology (ASCO) guideline published in 2005, the panel recommended routine ALND for macrometastases or micrometastases found on SLNB. On the other hand, appropriately identified patients with negative results of SLNB need not have completion of ALND. However, the panel also mentioned that
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there were insufficient data to determine whether ALND should be carried out in all cases with micrometastases or ITCs [16]. Therefore, preparation of pathological sections with 200–500 lm interval is described to be optimal. However, too meticulous examination is not realistic in the routine pathology work flow except for those institutes that specialize in breast cancer treatment. In Japan, the routine method of pathological diagnosis of SLN metastasis is not standardized because of difference in the system of pathological diagnosis and the problem of manpower among hospitals. The most prevailing procedure appears to be intraoperative pathological examination composed of cutting each SLN in parallel into 2-mm thick pieces, preparing frozen sections for each piece, fixing them briefly with formalin, and staining with HE. However, because of insufficient manpower, SLNs are often examined after bisection or a single section without cutting. Some institutes adopt preoperative SLNB and subject the biopsied SLNs for permanent sections. In the permanent pathology section, it is easy to dissect formalin-fixed sentinel nodes into 2-mm thick pieces and to visualize subcapsular area. In the Department of Pathology, National Cancer Center Hospital, Tokyo, each SLN was sliced in parallel with shorter axis into 2-mm thick pieces, and each peace was put on nitrocellulose filter to be able to examine sub-capsular area and parenchyma of the SLN, and subjected to frozen sections. In the Department of Pathology, National Defense Medical College, each SLN was sliced in parallel with shorter axis into 2-mm thick pieces, and the method of Kawamoto was also used for visualizing subcapsular area and avoidance of bending or overlapping of a section [17]. With these means, the chances to overlook macrometastasis or micrometastasis may decrease. After intraoperative frozen section diagnosis, the tissue pieces of SLNs are fixed in 10 % formalin and subjected to permanent histopathological diagnosis. In the early in-house studies, the percentage of overlooking metastatic foci in metastasis-positive SLNs in frozen section diagnosis is reported to be 11–43 % in total metastasis-positive SLNs [reviewed in 18]. Exceptionally, Veronesi U et al. achieved an excellently low false-negative rate (5.5 %) in true metastasis-positive lymph nodes by means of exhaustive method: A bisected lymph node along its major axis was subjected to preparation of 4-lm thick frozen sections cut at 50-lm intervals, amounting to around 60 sections per lymph node (30 sections per half lymph node). One section of each pair was stained with HE: if HE was negative or doubtful, the other was stained for cytokeratins using a rapid immunohistochemical method [19]. Intraoperative imprint cytopathological examination (Giemsa stain and/or HE stain) was also reported to be able to accurately identify these metastases [9, 20]. In some hospitals, combined use of HE and IHC
examinations or the use of cytopathological examination is introduced into intraoperative diagnosis. A major problem with cytopathology consists in the difficulty in measuring the diameters of metastatic foci. There are reports that immunohistochemistry using an anti-cytokeratin antibody (e.g., AE1/AE3 or CAM5.2) is useful to identify metastatic foci that were overlooked with HE. Especially, this method is useful to detect metastasis of invasive lobular carcinoma because difficulty in the identification of metastasis foci is well known for invasive lobular carcinoma by intraoperative HE or imprint cytology only [13, 21].
Clinical implication of micrometastasis and ITCs in SLNs In 2001, by employing the ‘‘exhaustive method’’ above, Viale et al. [22] studied 109 patients who had micrometastasis in SLNs and underwent both SNB and complete ALND. The overall frequency of metastasis to non-SLNs was 21.8 %, and the frequency of non-SLN metastases was correlated with the size of the SLN micrometastatic focus: 36.4 % of patients with foci [1 mm whereas only 15.6 % of patients with foci if 1 mm or less. If the diameter of SLN metastasis was [2.0 mm (macrometastasis), 44.7 % of the patients had non-SLN metastasis [22]. Even if SLNs had occult metastases, detected only by immunohistochemistry, 10–15 % of patients had non-SLN metastases by HE [22]. In a meta-analysis by Cserni G et al. [23], around 20 % of patients who were positive of micrometastasis in a SLN showed metastasis in non-SLNs. In contrast, in patients with metastatic foci detectable by immunohistochemistry a SLN only, metastasis in non-SLNs was detected in 9 % [23]. van Deurzen CHM et al. [24] reported in their meta-analysis that overall pooled risk for non-SLN involvement in patients with ITCs in SLNs was 12.3 %. Therefore, results on ITCs in the SLN were somewhat controversial, although ITCs were not regarded as metastases in UICC/TNM classification and AJCC classification. Regarding policies on ALND after the identification of a positive SLN, greater clinical evidence from large clinical trials was waited.
Retrospective studies de Boer et al. [25] performed a retrospective study, named MIRROR (Micrometastases and Isolated Tumor Cells: Relevant and Robust or Rubbish?), to draw evidence concerning micrometastases and prognosis in patients with early breast cancer who received SLNB using nationwide data of the Netherlands Cancer Registry. Their study
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randomly included 856 women with node-negative disease who did not receive systemic adjuvant therapy, other 856 women with ITCs or micrometastases who did not receive adjuvant therapy, and 994 women with ITCs or micrometastases who received adjuvant therapy. All these three cohorts contained patients who received both types of surgery (breast-conserving surgery in 71.0 % and mastectomy in 29.0 % in total) and patients with ALND (49.4 % in total) and without (50.6 % in total). In pathological review in their study, handling of lymph nodes was as follows: SLNs were examined for widely spaced step sections (at minimum 3 sections cut at least at 150-lm intervals). These sections were stained with HE, and immunohistochemistry was added in HE-negative cases. For non-SLNs, 2- to 5-mm interval sections were made and stained with HE only. By the comparison of patient prognosis between the 856 patients of the node-negative, no-adjuvant therapy cohort and the 856 patients of node-positive (micrometastasis or ITCs), no-adjuvant therapy cohort, the unadjusted 5-year disease-free survival (DFS) rate in the latter cohort was significantly reduced (nearly 10 %) as compared with that in the former cohort (76.5 vs 85.7 %, P \ 0.001) [25]. Among the 856 patients with micrometastasis or ITCs, the unadjusted 5-year DFS rate was similar between the patient subset with ITCs and the patient subset with micrometastases (77.2 and 75.9 %, respectively; P = 0.77). Among patients with ITCs or micrometastases, the unadjusted 5-year DFS rate in the node-positive, no-adjuvant-therapy cohort subset was significantly reduced (nearly 10 %) as compared with that rate in the nodepositive, adjuvant-therapy cohort subset (76.5 and 86.2 %, P \ 0.001). Among the patients with ITCs only, the patient subset that did not receive adjuvant therapy had a significantly reduced 5-year DFS rate as compared with patient cohort that received adjuvant therapy (77.2 and 83.0 %, P = 0.04). Among patients with micrometastases, the patient cohort that did not receive adjuvant therapy had a significantly reduced 5-year DFS rate as compared with the patient cohort that received adjuvant therapy (75.9 and 87.9 %, P \ 0.001) [25]. From these results, they concluded that DFS was improved by adjuvant systemic therapy in patients with ITCs or micrometastases. In the study of de Boer et al. [26], central pathology review was adopted for the purpose of quality control of nodal breast cancer staging. The discrepancy between the local pathologists and review pathologists was high resulting in 24 % changes of the final pN status (kappa coefficient of 0.69). The 5-year DFS was better for all subgroups considering the classification as assessed by the review pathologists. de Boer et al. [27] also conducted a systematic review of prognostic relevance of micrometastases and ITCs in lymph nodes from patients with breast cancer and concluded that the presence (vs the absence) of metastases of
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2 mm or less in diameter in axillary lymph nodes detected on single-section examination was associated with poorer DFS and overall survival (OS). Another study showed different results. Using a cohort of 790 patients in the John Wayne Cancer Institute, Santa Monica, CA, between 1992 and 1999, Hansen NM et al. [28] examined the effect of micrometastasis on patients’ clinical outcome. In their study, [90 % the patients with macrometastasis, micrometastasis, and ITCs received adjuvant systemic therapies (91, 96, and 93 %, respectively) and 66 % of patients of pN0 group also received adjuvant systemic therapies. Pathological review was performed as follows: each SLN was bisected and blocked, prepared for permanent sectioning, and stained with HE. If negative, 6–8 sections of the SLN were submitted for immunohistochemistry using a monoclonal antibody against cytokeratins [28]. At a median follow-up of 72.5 months the size of SLN metastases was a significant predictor of DFS and OS. There was no statistically significant difference in 8-year DFS and 8-year OS among the patient groups with micrometastasis (92.05 and 94.11 %), with ITCs (97.57 and 100 %), and with pN0 (95.86 and 96.85 %) [27]. In contrast, there was a significant difference in 8-year DFS and 8-year OS for macrometastasis group (82.50 and 88.40 %) (P \ 0.0001 and P \ 0.001) [28].
Prospective studies The incidence of the metastases that are overlooked in routine pathological examinations, that is, ‘‘occult metastases’’, is reported to be 9 to 30 %, and most of these occult metastases are micrometastases or ITCs. In 2011–2013, the results of three prospective randomized studies relevant to SLN metastasis were published in the National Surgical Adjuvant Breast and Bowel Project (NSABP) trial B-32, the International Breast Cancer Study Group (IBCSG) trial 23-01, and the American College of Surgeons Oncology Group (ACOSOG) trial Z0011 [29–31]. The NSABP B-32 trial aimed to determine whether SLN resection in breast cancer patients achieved the same survival and regional control as axillary dissection but with fewer side effects [29]. 5,611 women with invasive breast cancer were randomly assigned to SLN resection plus ALND (Group 1) or to SLN resection alone with ALNB only if SLNs were positive (Group 2). Because planned surgical treatment was randomized within each participating institution, the percentage of lumpectomy (87.7 and 87.0 %) and mastectomy (12.3 and 13.0 %) was almost equal between SLN resection plus ALND group and SLN resection-only group. The use of systemic adjuvant therapy and radiation therapy was also well balanced: 85 % of Group 1 and 84.1 % of Group 2 patients received systemic
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adjuvant therapy and 82.3 % of Group 1 and 82.2 % of Group 2 patients received radiation therapy. SLNs from both Groups 1 and 2 were evaluated postoperatively with routine stains at approximately 2-mm intervals through the node. Immunohistochemistry was not permitted except for confirmation of suspicious findings on routine HE stains [29]. Among the 3,986 SLN-negative women with follow-up information, 8-year OS of Group 1 and 2 was 91.8 and 90.3 %, respectively (P = 0.12), and 8-year DFS of Group 1 and 2 was 82.4 and 81.5 %, respectively (P = 0.54). Regional node recurrence rates between Groups 1 and 2 did not differ significantly (P = 0.22) [29]. NSABP B-32 also studied clinical significance of occult metastasis in SLNs [32]. This trial examined whether patients with initially negative SLNs who have occult metastases detected on deeper levels and cytokeratin immunohistochemistry stains are a risk for regional or distant metastases. Tissue blocks of the SLNs obtained from all pN0 patients by the participating site were subjected to the central institute for the evaluation of occult metastases. One HE section and one cytokeratin immunohistochemistry section were evaluated at two levels—approximately 0.5 mm and 1.0 mm—deeper into the paraffin block (four sections total). This two-level, widely spaced protocol was designed to exclude micrometastases larger than 1.0 mm from the ‘‘occult metastases negative’’ group (Fig. 1) [33]. In 3,884 routinely pN0 patients with follow-up data, occult metastases were detected in 616 (15.9 %), 11.1 % being ITC clusters, 4.4 % micrometastases, and 0.4 % macrometastases. Therefore, most of the occult metastases were ITCs or micrometastases [32]. In these routine pN0 patients, the detection of occult metastasis was a significant risk factor: 5-year regional recurrence rate in 616 pN0 patients with occult metastases was 1.1 %, and the rate in 300 pN0 patients with occult metastases who underwent SLNB without ALND was 1.7 %. In contrast, 5-year regional recurrence rate in 3,268 pN0 patients without occult metastases was 0.4 %, and the rate in 1660 pN0 patients with occult metastases who underwent SLNB without ALND was 0.5 %. Likewise, in pN0 patients who underwent SLNB without ALND, there was a significant difference in OS, DFS, and distant DFS between patients with occult metastases and those without [32, 33]. The authors concluded that, however, difference in outcome at 5 years was small between these two groups [31, 32]. These data do not indicate a clinical benefit of additional evaluation, including immunohistochemical analysis, of initially negative SLNs in patients with breast cancer [29]. Systemic adjuvant therapy was more often administered in the patient group with occult metastases, and it was hypothesized that without systemic adjuvant
therapy the difference in adverse outcome might nave been be larger [32]. The IBCSG 23-01 was a phase III study that randomized those patients with micrometastasis or ITCs in the SLNs, based on HE pathology examination, to ALND or no ALND, to assess (like ACOSOG Z0011) the impact of avoiding ALND on long-term patient outcomes [30]. In that study, enrollment was limited to patients with micrometastases or ITCs, and 95.6 % of patients had only one positive SLN limited to ITCs or micrometastases. Breast conservation surgery with radiation was performed for 88.4 % of the enrolled patients and 96 % of patients received systemic therapy. In the IBCSG 23-01, all SLNs were entirely sectioned at 50–200 lm intervals, and each section (frozen or permanent) was examined by HE. Cytokeratin immunostaining was used only when the presence of micrometastasis was suspected, but not certain, or not determined, on HE sections. That study was conducted in a time frame in which surgeons were already adapting their practices and decreasing their performance of ALND for micrometastatic SLN disease, and closed early after meeting less than 50 % of its targeted accrual goal [30, 34]. Regional recurrence rates and DFS rates (1 % vs 87.8 %, respectively) of the no-ALND group were not different from those (0.2 % and 84.4 %, respectively) of the ALND group after a 5-year median follow-up, and ALND might be avoided safely in the patients with early breast cancer (\3 cm tumor) with ITCs or micrometastases, receiving breast conservation surgery with radiation, and adjuvant systemic therapy [30, 34]. The common conclusion from NSABP B-32 and IBCSG 23-01 was that, compared with SLNB alone, completion of ALND does not appear to improve outcomes for breast cancer patients with microscopic nodal metastases. A larger impact in practice of axillary management in breast cancer patients was derived from the result of the ACOSOG Z0011 trial. This study was designed as a phase III non-inferiority trial to determine whether completion of ALND for breast cancer patients with SLN metastasis, undergoing breast conservation surgery and adjuvant whole-breast irradiation, affects overall survival [31]. Eligibility criteria included patients with cT1-2, cN0 invasive breast cancer, and one or two SLN metastasis without extranodal extension detected by frozen section, imprint cytology or HE staining on permanent section. Patients with breast cancer to the SLN identified by immunohistochemistry were not eligible. Not only patients with micrometastases but also those with macrometastases to SLNs were included. All patients received breast conservation surgery and SLNB, with histologically negative margins of the lumpectomy specimen. Patients with metastasis in one
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to two SLNs were randomly assigned into ALND or noALND groups. Whole-breast irradiation was administered after surgery via two tangential fields. More than 90 % of patients received systemic therapy [31, 34, 35]. Similar to the IBCSG 23-01 study, the Z0011 study was also closed early after meeting less than 50 % of its targeted accrual goal. The ACOSOC Z0011 allowed micrometastatic or macrometastatic disease in the SLNs, different from the IBCSG 23-01 study that limited enrollment to patients with micrometastases or ITCs. In ACOSOG Z0011 study, 50 % of patients (430 of 856) had macrometastatic disease, 35 % (301 of 856) had micrometastases, and the remainder no or unknown extent of nodal disease [31, 34]. In addition, in the Z0011 study, 79 % (324 of 415) of the SLN only group had zero or one metastasis-positive SLN, whereas in the IBCSG study, 95 % of patients had only one metastasispositive SLN. Therefore, nodal burden was higher in the ACOSOG Z0011 study than in the IBCSG 23-01 [35]. At a median follow-up of 6.3 years, the use of SLN dissection alone compared with ALND did not appear to result in statistically inferior survival (P = 0.008 for noninferiority). The 5-year OS rates were 92.5 % in the SLN dissection-alone group and 91.8 % in the ALND group (P = 0.25). The 5-year DFS rates were 83.9 % for the SLN dissection-alone group and 82.2 % for the ALND group (P = 0.14) [31]. The 5-year total locoregional recurrence rate in the SLN dissection-alone group was 2.5 % compared with 3.6 % in the ALND group. Therefore, it was indicated that the addition of ALND does not benefit in terms of local control, DFS, or OS to the patients with clinical T1-2 tumors and a positive SLN metastasis who underwent breast-conserving therapy followed by systemic therapy [31]. With the results of previous studies that support the omission of ALND, the Z0011 study results were incorporated in clinical practice guidelines [36, 37]. In these guidelines, it is described that clinicians should not recommend ALND for women with early-stage breast cancer and one or two SLN metastases who will undergo breast conservation surgery with conventionally fractionated whole-breast radiotherapy. It is also recommended that the clinician may offer ALND for women with early-stage breast cancer with nodal metastases found on SLNB who will undergo mastectomy [37]. The European Organization for Research and Treatment of Cancer (EORTC) 10981-22023 AMAROS (the After Mapping of the Axilla: Radiotherapy or Surgery) trial is a randomized, multicenter, phase III non-inferiority trial in patients with T1-2 primary, unifocal, invasive breast cancer, with no palpable lymphadenopathy to investigate as to whether breast cancer patients with a tumor-positive SLN are best treated with an ALND or axillary radiotherapy
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[38]. Before the SLNB procedure, patients were randomized between ALND and axillary radiotherapy. Pathological SLN examination in the AMAROS protocol was as follows: As a minimal requirement, three histological levels (500-lm distance) for each SLN were examined. On each level, two parallel sections were performed, one for immunohistochemistry for cytokeratins and one for HE. Immunohistochemical staining was required only when HE staining was negative. The SLN was considered tumor-positive if any tumor deposit in the node or in the afferent or efferent lymph vessels was found. Tumor deposits were categorized as ITCs, micrometastases, or macrometastases according to UICC/TNM classification, 6th edition. After protocol amendment in 2008, SLNs with only ITCs were no longer regarded as SLN positive [38, 39]. Local treatment of the breast consisted of breast-conserving therapy including whole-breast radiotherapy or mastectomy with or without irradiation of the chest wall. Adjuvant axillary radiotherapy after ALND was allowed when at least 4 positive nodes were found. The use of adjuvant systemic treatment was at the discretion of treating multidisciplinary team. The primary endpoint in the group of SLN-positive patients was 5-year axillary recurrence. Among the SLNpositive patient group, breast-conserving surgery was performed for 82 % in both the ALND subgroup (n = 744) and the axillary radiotherapy subgroup (n = 681), and mastectomy was performed for 17 and 18 % of these subgroups, respectively. The number of positive SLNs was 1 or 2 in 95 % of both the ALND subgroup and the axillary radiotherapy subgroup, and the largest SLN metastases in the ALND subgroup and axillary radiotherapy subgroup were macrometastasis in 59 and 62 %, micrometastasis in 29 and 29 %, and ITCs in 12 and 10 %, respectively [38]. Systemic adjuvant therapy was administered for 90 % of the patients in both subgroups. The interim report of the AMAROS study assessed the further nodal involvement in macromeastases, micrometastases, and ITCs, separately, in the SLN-positive ALND group [39]: Further nodal involvement was seen in 41, 18, and 18 % of the patients with macrometastases, micrometastases, and ITCs, respectively, and extensive nodal involvement (4 or more) was slightly higher in patients with micrometastases (6 %) than in ITCs (3 %). In the patients with positive SLNs, with median followup period of 6.1 years, 5-year axillary recurrence was 0.43 % after ALND versus 1.19 % after axillary radiotherapy. There were no significant differences in DFS and OS between these treatment groups: 5-year DFS and OS were 86.9 and 93.3 % in the ALND group and 82.7 and 92.5 % in the axillary radiotherapy group and the axillary radiotherapy group, respectively. The axillary radiotherapy
Breast Cancer b Fig. 2 A schematic presentation of the methods for pathological SLN
A 150 µm 150 µm
B 2 mm 2 mm 2 mm
C
0.5 mm 1.0 mm 0.5 mm 1.0 mm
D 50
200 µm
E 500 µm 500 µm
seemed to be non-inferior to ALND in the population of patients with clinically node negative axilla and a positive SLN. The AMAROS study cannot answer the remaining question of which subset of clinically node-negative, SLNpositive patients still require axillary treatments. Nonetheless, if further axillary treatment is needed in clinically node-negative, SLN-positive patients, axillary radiotherapy could be chosen instead of ALND [38].
Discussion Internationally, there is no consensus on the pathology protocol to be used to examine the SLN in breast cancer patients except that a node should be cut no thicker than 2 mm [37, 40]. The methods for pathological SLN examination employed in the major protocol studies are schematically presented in Fig. 2, according to the description in the journals. Histological examination was performed at three levels on an average except for the IBCSG 23-01 and part of occult metastasis study in the NASBP B-32 [25, 29–32].
examination employed in the protocol studies. A. MIRROR trial [25]. SLNs were examined for widely spaced step sections (at minimum 3 sections cut at least at 150-lm intervals). The sections were stained with HE, and immunohistochemistry was added in HE-negative cases. For non-SLNs, 2- to 5-mm interval sections were made and stained with HE only. B. NSABP B-32 trial [29]. SLNs were evaluated postoperatively with routine stains at approximately 2-mm intervals through the node. Immunohistochemistry was not permitted except for confirmation of suspicious findings on routine HE stains. C. NSABP B-32 trial for detection of occult micrometastases and isolated tumor cells [32]. Tissue blocks of the SLNs obtained from all pN0 patients by the participating site were subjected to the central institute for the evaluation of occult metastases. One HE and cytokeratin immunohistochemical stained section was evaluated at two levels—approximately 0.5 mm and 1.0 mm—deeper into the paraffin block (four sections total). This two-level, widely spaced protocol was designed to exclude micrometastases larger than 1.0 mm from the ‘‘occult metastases negative’’ group. D. IBCSG 23-01 trial [30]. All SLNs were entirely sectioned at 50–200 lm intervals and each section (frozen or permanent) was examined by HE staining. Cytokeratin immunostaining was used only when the presence of micrometastasis was suspected but not certain, or not determiner, on HE sections. E. AMAROS trial [38]. As a minimal requirement, three histological levels (500 lm distance) for each SLN were examined. On each level, two parallel sections were performed, one for immunohistochemistry for cytokeratins and one for HE. Immunohistochemical staining was required only when HE staining was negative
From the results of these studies, not only macrometastasis but also micrometastases or ITCs in SLNs are accompanied relatively frequently by non-SLN metastases [25, 29–32]. In a retrospective study, micrometastases and ITCs in SLNs were certainly indicators for worse clinical outcome of breast cancer patients when systemic adjuvant therapy was not undergone [25]. In prospective randomized studies, the impact of micrometastases and ITCs on patients’ clinical outcome was not large even if differences in the rates of locoregional recurrence, DFS, and/or OS were statistically significant [29, 30]. In these prospective studies, most of the patients who were entered in the arm of SLNB only without ALND received breast-conserving therapies, most of which included lumpectomy and whole-breast irradiation, and systemic adjuvant therapies. Therefore, it was highly probable that the residual non-SLN metastases in these patients disappeared by these therapies, which caused decrease in the rates of regional recurrence, DFS, and OS. With regard to the results in the retrospective study by Hansen NM et al. [28], similar interpretation was possible. At present, there are no data about the clinical implication of SLN micrometastases/ITCs in cN0 breast cancer patients who received mastectomy without axillary irradiation. Interobserver inconsistency in the diagnosis of small foci of SLN metastases is shown by several protocol studies. Such inconsistency may derive from the ambiguity with the classification and lack in consensus acquisition among
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pathologists prior to the study [12, 40]. For providing standardized pathology criteria and definition, the incorporation of the number of metastatic cancer cells as well as the largest diameter of metastatic foci will be important [13]. Turner RR et al. [12] stated that training program using illustrative examples with electronic archives would be helpful for the improvement of interobserver agreement in the diagnosis of small SLN metastasis. Central pathology review might contribute to quality assurance of nodal breast cancer staging in protocol studies [26]. We are able to learn much about how large-scale protocol studies incorporate pathology practice. In Japan, one of the issues involves evidence acquisition about one-step nucleic acid amplification (OSNA) method that is introduced for intraoperative SLN diagnosis [41–43]. An OSNA-positive SLN is categorized as pN0(mol?) in UICC/TNM classification, 7th edition [14, 15]. However, the concept of development of OSNA is largely the decrease in the burden of pathology practice. In most institutes introducing OSNA method, the entire SLNs are used up for this assay, and no tissue blocks remain for permanent pathology diagnosis. To establish state-of-the- art surgical axillary management using OSNA, large-scale clinical trials of OSNA version and clarification of concordance between SLN diagnoses by OSNA and by pathology might be required. In conclusion, clinical implication of micrometastases and ITCs has been clarified by multiple large-scale retrospective and prospective studies. Although pathological detection of micrometastases and ITCs in the SLNs are indicators of worse clinical outcome of patients with clinically node-negative breast cancer, such negative effects appeared to be much decreased by systemic adjuvant therapy and irradiation in case of breast-conserving therapy. A similar effect would operate in the patients with breast cancer with macrometastases to 1–2 SLNs who received systemic adjuvant therapy and breast-conserving therapy with irradiation. For the assurance of quality in clinical trials, consensus on the protocol for pathological examination of SLNs and standardization of pathological classification of SLN metastasis would be important. Acknowledgments This work was supported in part by the National Cancer Center Research and Development Fund and from the Grandin-Aid of the Ministry of Health, Labor, and Welfare, Japan. Conflict of interest interest.
The author declares that there is no conflict of
References 1. Cavanas R. An approach for the treatment of penile carcinoma. Cancer. 1977;39:456–66.
123
2. Morton DL, Wen DR, Wong JH, Economou JS, Cagle LA, Storm FK, et al. Technical details of intraoperative lymphatic mapping for early stage melanoma. Arch Surg. 1992;127:392–9. 3. Krag DN, Weaver DL, Alex JC, Fairbank JT. Surgical resection and radio-localization of the sentinel node in breast cancer using a gamma probe. Surg Oncol. 1993;2:335–40. 4. Giuliano AE, Kirgan DM, Guenther JM, Morton DL. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg. 1994;220:391–401. 5. Veronesi U, Paganelli G, Viale G, Luini A, Zurrida S, Galimberti V, et al. A randomized comparison of sentinel-node biopsy with routine axillary dissection in breast cancer. N Engl J Med. 2003;349:546–53. 6. Mansel RE, Fallowfield L, Kissin M, Goyal A, Newcombe RG, Dixon JM, et al. Randomized multicenter trial of sentinel node biopsy versus standard axillary treatment in operable breast cancer: the ALMANAC Trial. J Natl Cancer Inst. 2006;98:599–609. 7. Noguchi M, Tsugawa K, Bando E, Kawahara F, Miwa K, Yokoyama K, et al. Sentinel lymphadenectomy in breast cancer: identification of sentinel lymph node and detection of metastases. Breast Cancer Res Treat. 1999;53:97–104. 8. Sato K, Hiraide H, Uematsu M, Tamaki K, Ishikawa H, Yamasaki T, et al. Efficacy and significance of sentinel lymph node identification with technetium-99m-labeled tin colloids for breast cancer. Breast Cancer. 1998;5:389–93. 9. Motomura K, Inaji H, Komoike Y, Kasugai T, Nagumo S, Noguchi S, et al. Sentinel node biopsy in breast cancer patients with clinically negative lymph nodes. Breast Cancer. 1999;6:259–62. 10. Sobin LH, Wittekind C. TNM classification of malignant tumours. International Union against Cancer. 6th ed. New York: Wiley-Liss; 2002. 11. Singletary SE, Allred C, Ashley P, Bassett LW, Berry D, Bland KI, et al. Revision of the American Joint Committee on Cancer staging system for breast cancer. J Clin Oncol. 2002;20:3628–36. 12. Turner RR, Weaver DL, Cserni G, Lester SC, Hirsch K, Elaschoff DA, et al. Nodal stage classification for breast carcinoma: improving interobserver reproducibility through standardized histologic criteria and image-based training. J Clin Oncol. 2008;26:258–63. 13. Apple SK, Moatamed NA, Finck RH, Sullivan PS. Accurate classification of sentinel lymph node metastases in patients with lobular breast carcinoma. Breast. 2010;19:360–4. 14. Sobin L, Gospodarowicz M, Wittekind C. TNM Classification of malignant Tumours. International Union Against Cancer. 7th ed. Chichester: Wiley; 2010. 15. Edge SB, Byrd DR, Compton CC, Fritz AG, Greene FL, Trotti A. AJCC Cancer Staging Manual. 7th ed. New York: Springer; 2010. 16. Lyman GH, Giuliano AE, Somerfield MR, Benson AB III, Bodurka DC, Burstein HJ, et al. American Society of Clinical Oncology. American Society of Clinical Oncology guideline recommendations for sentinel lymph node biopsy in early-stage breast cancer. J Clin Oncol. 2005;23:7703–20. 17. Kawamoto T. Use of a new adhesive film for the preparation of multi-purpose fresh-frozen sections from hard tissues, wholeanimals, insects and plants. Arch Histol Cytol. 2003;66:123–43. 18. Chao C, Wong SL, Ackermann D, Simpson D, Carter MB, Brown CM, et al. Utility of intraoperative frozen section analysis of sentinel lymph nodes in breast cancer. Am J Surg. 2001;182:609–15. 19. Veronesi U, Paganelli G, Viale G, Galimberti V, Luini A, Zurrida S, et al. Sentinel lymph node biopsy and axillary dissection in breast cancer: results in a large series. J Natl Cancer Inst. 1999;91:368–73. 20. Aihara T, Munakata S, Morino H, Takatsuka Y. Comparison of frozen section and touch imprint cytology for evaluation of sentinel lymph node metastasis in breast cancer. Ann Surg Oncol. 2004;11:419–22.
Breast Cancer 21. Taras AR, Hendrickson NA, Pugliese MS, Lowe KA, Atwood M, Beatty JD. Intraoperative evaluation of sentinel lymph nodes in invasive lobular carcinoma of the breast. Am J Surg. 2009;197:643–7. 22. Viale G, Maiorano E, Mazzarol G, Zurrida S, Galimberti V, Luini A, et al. Histologic detection and clinical implications of micrometastases in axillary sentinel lymph nodes for patients with breast carcinoma. Cancer. 2001;92:1378–84. 23. Cserni G, Gregori D, Merletti F, Sapino A, Mano MP, Ponti A, et al. Meta-analysis of non-sentinel node metastases associated with micrometastatic sentinel nodes in breast cancer. Br J Surg. 2004;91:1245–52. 24. van Deurzen CHM, de Boer M, Monninkhof EM, Bult P, van der Wall E, Tjan-Heijnen VCG, et al. Non-sentinel lymph node metastases associated with isolated breast cancer cells in the sentinel node. J Natl Cancer Inst. 2008;100:1574–80. 25. de Boer M, van Deurzen CHM, van Dijck JAAM, Borm GF, van Diest PJ, Adang EMM, et al. Micrometastases or isolated tumor cells and the outcome of breast cancer. N Engl J Med. 2009;361:653–63. 26. Vestjens JHMJ, Pepels MJ, de Boer M, Borm GF, van Deurzen CHM, van Diest PJ, et al. Relevant impact of central pathology review on nodal classification in individual breast cancer patients. Ann Oncol. 2012;23:2561–6. 27. de Boer M, van Dijck JA, Bult P, Borm GF, Tjan-Heijnen VC. Breast cancer prognosis and occult lymph node metastases, isolated tumor cells, and micrometastases. J Natl Cancer Inst. 2010;102:410–25. 28. Hansen NM, Grube B, Ye X, Turner RR, Brenner RJ, Sim MS, et al. Impact of micrometastases in the sentinel node of patients with invasive breast cancer. J Clin Oncol. 2009;27:4679–84. 29. Krag DN, Anderson SJ, Julian TB, Brown AM, Harlow SP, Costantino JP, et al. Sentinel-lymph-node resection compared with conventional axillary-lymph-node dissection in clinically node-negative patients with breast cancer: overall survival findings from the NSABP B-32 randomised phase 3 trial. Lancet Oncol. 2010;11:927–33. 30. Galimberti V, Cole BF, Zurrida S, Viale G, Luini A, Veronesi P, et al. International Breast Cancer Study Group Trial 23-01 investigators. Axillary dissection versus no axillary dissection in patients with sentinel-node micrometastases (IBCSG 23-01): a phase 3 randomised controlled trial. Lancet Oncol. 2013;14:297305. Erratum in: Lancet Oncol. 2013;14:e254. 31. Giuliano AE, Hunt KK, Ballman KV, Beitsch PD, Whitworth PW, Blumencranz PW, et al. Axillary dissection vs no axillary dissection in women with invasive breast cancer and sentinel node metastasis. A randomizes clinical trial. JAMA. 2011;305:569–75. 32. Weaver DL, Ashikaga T, Krag DN, Skelly JM, Anderson SJ, Harlow SP, et al. Effect of occult metastases on survival in nodenegative breast cancer. N Engl J Med. 2011;364:412–21.
33. Weaver DL, Le UP, Dupuis SL, Weaver KAE, Harlow SP, Ashikaga T, et al. Metastasis detection in sentinel lymph nodes: comparison of a limited widely spaced (NSABP protocol B-32) and a comprehensive narrowly spaced paraffin block sectioning strategy. Am J Surg Pathol. 2009;33:1583–9. 34. Hieken TJ, Boughey JC. Axillary dissection versus no axillary dissection in patients with sentinel-node micrometastases: commentary on the IBCSG 23-01 Trial. Gland Surg. 2013;2:128–32. 35. Gatzemeier W, Mann GB. Which sentinel lymph-node (SLN) positive breast cancer patient needs an axillary lymph-node dissection (ALND)—ACOSOG Z0011 results and beyond. Breast. 2013;22:211–6. 36. Gradishar WJ, Anderson BO, Blair SL, Burstein HL, Cyr A, Elias AD, et al. NCCN breast cancer version 3. Clinical practice guidelines in oncology. J Natl Compr Cancer Netw. 2014;2014(12):542–90. 37. Lyman GH, Temin S, Edge SB, Newman LA, Turner RR, Weaver DL, et al. Sentinel lymph node biopsy for patients with early-stage breast cancer: American Society of Clinical Oncology. American Society of Clinical Oncology practice guideline update. J Clin Oncol. 2014;32:1365–83. 38. Donker M, van Tienhoven G, Straver ME, Meijnen P, van de Velde CJ, Mansel RE, et al. Radiotherapy or surgery of the axilla after a positive sentinel node in breast cancer (EORTC 10981-22023 AMAROS): a randomised, multicentre, open-label, phase 3 non-inferiority trial. Lancet Oncol. 2014;15:1303–10. 39. Straver ME, Meijnen P, van Tienhoven G, van de Velde CJ, Mansel RE, Bogaerts J, et al. Sentinel node identification rate and nodal involvement in the EORTC 10981-22023 AMAROS trial. Ann Surg Oncol. 2010;17:1854–61. 40. Bolster MJ, Pepels MJ, Wauters CAP, Schapers RFM, Meijer JWR, Strobbe LJA, et al. Is the sentinel lymph node pathology protocol in breast cancer patients associated with the risk of regional recurrence? Eur J Surg Oncol. 2013;39:437–41. 41. Tsujimoto M, Nakabayashi K, Yoshidome K, Kaneko T, Iwase T, Akiyama F, et al. One-step nucleic acid amplification for intraoperative detection of lymph node metastasis in breast cancer patients. Clin Cancer Res. 2007;13:4807–16. 42. Tamaki Y, Akiyama F, Iwase T, Kaneko T, Tsuda H, Sato K, et al. Molecular detection of lymph node metastases in breast cancer patients: results of a multi-center trial using the one-step nucleic acid amplification (OSNA) assay. Clin Cancer Res. 2009;15:2879–84. 43. Jimbo K, Kinoshita T, Suzuki J, Asaga S, Hojo T, Yoshida M, et al. Combination use of one-step nucleic acid amplification and conventional histological examination for intraoperative diagnosis of sentinel lymph node metastasis in patients with early breast cancer. Breast. 2013;22:1194–9.
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