JCP Online First, published on April 8, 2015 as 10.1136/jclinpath-2014-202799 Original article
False negative rate for intraoperative sentinel lymph node frozen section in patients with breast cancer: a retrospective analysis of patients in a single Asian institution Jolene Wong,1 Wei Sean Yong,2 Aye Aye Thike,3 Jabed Iqbal,3 Ahmed Syed Salahuddin,3 Gay Hui Ho,2 Preetha Madhukumar,2 Benita Kiat Tee Tan,2 Kong Wee Ong,2 Puay Hoon Tan3 1
Department of General Surgery, Singapore General Hospital, Singapore 2 Department of Surgical Oncology, National Cancer Centre, Singapore 3 Department of Pathology, Singapore General Hospital, Singapore Correspondence to Jolene Wong, 11 Hospital Drive, Singapore 169610; [email protected] Received 6 December 2014 Revised 18 March 2015 Accepted 19 March 2015
To cite: Wong J, Yong WS, Thike AA, et al. J Clin Pathol Published Online First: [please include Day Month Year] doi:10.1136/jclinpath2014-202799
ABSTRACT Background and objective Intraoperative frozen section of the sentinel lymph node (SLN) in clinically node negative breast cancer patients detects metastatic disease and enables axillary lymph node dissection to be performed in the same operative setting. Internationally, the false negative rate (FNR) for SLN biopsy ranges from 5.5% to 43%. The size of SLN metastasis has been identified as a key factor affecting FNR. We review our institutional experience on the accuracy of intraoperative SLN biopsy. Methods Data were collected retrospectively from patients undergoing SLN biopsy performed at Singapore General Hospital. The SLN was identified using blue dye, radioisotope or both. Frozen section was performed intraoperatively. When SLN was positive for metastasis on frozen section, completion axillary clearance was performed. False negative cases were defined as patients in whom a negative frozen section result was obtained, whose final permanent paraffin section was positive. We determined the FNR of SLN frozen section and evaluated the factors associated with it. Results A total of 2202 SLN biopsies were performed between January 2005 and June 2012. There were 89 false negative cases, of which there were 23 (25.8%) cases of isolated tumour cells (ITCs), 49 (55.1%) cases of micrometastasis, and 17 (19.1%) cases of macrometastasis. The overall FNR was 13.5%. FNR was 79.3% in ITCs, 59.8% in micrometastasis, and 3.1% in macrometastatic disease. Non-ductal histological subtype, absence of lymphovascular invasion and the size of SLN metastasis were identified as significant independent factors associated with a higher FNR. Conclusions FNRin our institution is acceptable when compared to other large centres. Failure to detect metastasis in frozen section in more than half of our patients was due to ITCs and micrometastasis.
negative was similar to patients who received upfront complete axillary dissection.7–10 As such, with the rationale of minimising the morbidity associated with axillary lymph node dissection (ALND),11–14 it is performed only when the SLN is positive for metastatic disease. Intraoperative frozen section (IFS) analysis of SLNs allows prompt detection of metastatic disease so that immediate ALND may be performed in the same operative setting. Internationally, false negative rates (FNRs) of IFS for SLNs range from 5.5% to 43%.15–19 This large inter-institutional variability may be attributed to differing institutional protocols and expertise available.15 19 The goal of this study is to determine the FNR of IFS of SLNs in breast cancer surgery in our institution and to define factors associated with false negativity.
INTRODUCTION
Identification of SLNs
In the context of breast cancer, the sentinel lymph node (SLN) refers to the lymph node that first receives lymph from the area of the breast containing the tumour. It is well established that in the presence of a negative SLN, the likelihood of further axillary involvement is very low.1–6 Long term results from randomised trials have demonstrated that overall survival rates in patients who received no axillary dissection when the SLN was
SLNs were identified using a combination of both vital blue dye and/or technetium-99m sulfur colloid.20 These were injected either intradermally above the tumour or peritumorally. Preoperative lymphoscintigraphy was used to identify draining axillary SLNs in selected cases at the surgeon’s discretion. A hand-held gamma probe was used to evaluate radioactive counts where technetium-99m sulfur colloid was utilised.
MATERIALS AND METHODS Patient selection The study was carried out under the approval of the Centralised Institutional Review Board of the Singapore Health Service. Data were retrospectively collected from patients who underwent SLN biopsy (SLNB) at Singapore General Hospital (SGH) between January 2005 and June 2012. All patients had a histopathologically proven diagnosis of breast cancer and clinically negative axilla. Patients with ductal carcinoma in situ or prior neo-adjuvant chemotherapy were excluded from this study. Consent was taken for either partial or total mastectomy with SLNB; and patients were counselled for the likelihood of ALND in the same operative setting should the SLN be positive for metastatic disease. A total of 2202 SLN biopsies were performed during the assigned time period.
Wong J, et al. J Clin Pathol 2015;0:1–5. doi:10.1136/jclinpath-2014-202799
Copyright Article author (or their employer) 2015. Produced by BMJ Publishing Group Ltd under licence.
1
Original article IFS analysis of SLNs Identified SLNs were submitted for IFS evaluation. The lymph nodes were sliced at 2 mm intervals, frozen in liquid nitrogen and cryosectioned to produce 3–6 levels of 5 μm thick frozen sections (FSs). These were then stained with H&E and examined for the presence of metastasis. Metastases were classified as either micrometastatic (tumour deposits of size up to 2 mm in the greatest dimension) or macrometastatic (deposits more than 2 mm in size). Isolated tumour cells (ITCs) were defined as tumour foci measuring up to 0.2 mm. The frozen material as
Table 1 Clinicopathological characteristics of patients
Total Tumour grade Among patients with non-missing data Grade 1 Grade 2 Grade 3 Tumour size, mm Among patients with non-missing data T1a (≤5) T1b (>5–≤10) T1c (>10–≤20) T2 (>20–≤50) T3 (>50) Median (range) Lymphovascular involvement (LVI) Among patients with non-missing data Yes No Oestrogen receptor Among patients with non-missing data Positive Negative Progesterone receptor Among patients with non-missing data Positive Negative HER2 Among patients with non-missing data Positive Negative Histology Among records with non-missing data IDC ILC Mucinous Tubular Metaplastic Papillary Cribriform Medullary Neuroendocrine Apocrine Adenoid cystic Adenosquamous IDC and ILC IDC and Mucinous
No.
%
2202
100.0
2021 305 818 898
100.0 15.1 40.5 44.4
2069 68 183 741 973 104 22.0 (0.5–500.0)
100.0 3.3 8.8 35.8 47.0 5.0
2201 442 1759
100.0 20.1 79.9
1951 1495 456
100.0 76.6 23.4
1950 1384 566
100.0 71.0 29.0
1908 427 1481
100.0 22.4 77.6
2078 1801 98 65 30 5 22 13 11 2 2 1 1 22 5
100.0 86.7 4.7 3.1 1.4 0.2 1.1 0.6 0.5 0.1 0.1 0.1 0.1 1.1 0.2
well as any unfrozen SLN tissue were fixed and embedded in paraffin. Serial sections were stained with H&E and examined microscopically. Immunohistochemical (IHC) stains for CAM5.2 and AE1:AE3 were used only when the presence of cells suspicious of metastases were seen on H&E sections, needing IHC verification.
Statistical analysis Outcomes of the IFS of SLN were compared with that based on final histopathological analysis of the paraffin section of SLN for standard computation of FNR, sensitivity (Se), negative predictive value (NPR) and false NPR. False negative cases were defined as patients in whom a negative FS result was obtained, and whose final permanent paraffin section was positive. FNR was defined as (false negative)/(true positive+false negative). The sensitivity of IFS was defined as (true positive)/(true positive+false negative). Logistic regression models were fitted to estimate the ORs to assess the association of various variables with a false negative diagnosis of IFS of SLN. Multivariable analyses were performed on variables with p
False negative rate for intraoperative sentinel lymph node frozen section in patients with breast cancer: a retrospective analysis of patients in a single Asian institution Jolene Wong,1 Wei Sean Yong,2 Aye Aye Thike,3 Jabed Iqbal,3 Ahmed Syed Salahuddin,3 Gay Hui Ho,2 Preetha Madhukumar,2 Benita Kiat Tee Tan,2 Kong Wee Ong,2 Puay Hoon Tan3 1
Department of General Surgery, Singapore General Hospital, Singapore 2 Department of Surgical Oncology, National Cancer Centre, Singapore 3 Department of Pathology, Singapore General Hospital, Singapore Correspondence to Jolene Wong, 11 Hospital Drive, Singapore 169610; [email protected] Received 6 December 2014 Revised 18 March 2015 Accepted 19 March 2015
To cite: Wong J, Yong WS, Thike AA, et al. J Clin Pathol Published Online First: [please include Day Month Year] doi:10.1136/jclinpath2014-202799
ABSTRACT Background and objective Intraoperative frozen section of the sentinel lymph node (SLN) in clinically node negative breast cancer patients detects metastatic disease and enables axillary lymph node dissection to be performed in the same operative setting. Internationally, the false negative rate (FNR) for SLN biopsy ranges from 5.5% to 43%. The size of SLN metastasis has been identified as a key factor affecting FNR. We review our institutional experience on the accuracy of intraoperative SLN biopsy. Methods Data were collected retrospectively from patients undergoing SLN biopsy performed at Singapore General Hospital. The SLN was identified using blue dye, radioisotope or both. Frozen section was performed intraoperatively. When SLN was positive for metastasis on frozen section, completion axillary clearance was performed. False negative cases were defined as patients in whom a negative frozen section result was obtained, whose final permanent paraffin section was positive. We determined the FNR of SLN frozen section and evaluated the factors associated with it. Results A total of 2202 SLN biopsies were performed between January 2005 and June 2012. There were 89 false negative cases, of which there were 23 (25.8%) cases of isolated tumour cells (ITCs), 49 (55.1%) cases of micrometastasis, and 17 (19.1%) cases of macrometastasis. The overall FNR was 13.5%. FNR was 79.3% in ITCs, 59.8% in micrometastasis, and 3.1% in macrometastatic disease. Non-ductal histological subtype, absence of lymphovascular invasion and the size of SLN metastasis were identified as significant independent factors associated with a higher FNR. Conclusions FNRin our institution is acceptable when compared to other large centres. Failure to detect metastasis in frozen section in more than half of our patients was due to ITCs and micrometastasis.
negative was similar to patients who received upfront complete axillary dissection.7–10 As such, with the rationale of minimising the morbidity associated with axillary lymph node dissection (ALND),11–14 it is performed only when the SLN is positive for metastatic disease. Intraoperative frozen section (IFS) analysis of SLNs allows prompt detection of metastatic disease so that immediate ALND may be performed in the same operative setting. Internationally, false negative rates (FNRs) of IFS for SLNs range from 5.5% to 43%.15–19 This large inter-institutional variability may be attributed to differing institutional protocols and expertise available.15 19 The goal of this study is to determine the FNR of IFS of SLNs in breast cancer surgery in our institution and to define factors associated with false negativity.
INTRODUCTION
Identification of SLNs
In the context of breast cancer, the sentinel lymph node (SLN) refers to the lymph node that first receives lymph from the area of the breast containing the tumour. It is well established that in the presence of a negative SLN, the likelihood of further axillary involvement is very low.1–6 Long term results from randomised trials have demonstrated that overall survival rates in patients who received no axillary dissection when the SLN was
SLNs were identified using a combination of both vital blue dye and/or technetium-99m sulfur colloid.20 These were injected either intradermally above the tumour or peritumorally. Preoperative lymphoscintigraphy was used to identify draining axillary SLNs in selected cases at the surgeon’s discretion. A hand-held gamma probe was used to evaluate radioactive counts where technetium-99m sulfur colloid was utilised.
MATERIALS AND METHODS Patient selection The study was carried out under the approval of the Centralised Institutional Review Board of the Singapore Health Service. Data were retrospectively collected from patients who underwent SLN biopsy (SLNB) at Singapore General Hospital (SGH) between January 2005 and June 2012. All patients had a histopathologically proven diagnosis of breast cancer and clinically negative axilla. Patients with ductal carcinoma in situ or prior neo-adjuvant chemotherapy were excluded from this study. Consent was taken for either partial or total mastectomy with SLNB; and patients were counselled for the likelihood of ALND in the same operative setting should the SLN be positive for metastatic disease. A total of 2202 SLN biopsies were performed during the assigned time period.
Wong J, et al. J Clin Pathol 2015;0:1–5. doi:10.1136/jclinpath-2014-202799
Copyright Article author (or their employer) 2015. Produced by BMJ Publishing Group Ltd under licence.
1
Original article IFS analysis of SLNs Identified SLNs were submitted for IFS evaluation. The lymph nodes were sliced at 2 mm intervals, frozen in liquid nitrogen and cryosectioned to produce 3–6 levels of 5 μm thick frozen sections (FSs). These were then stained with H&E and examined for the presence of metastasis. Metastases were classified as either micrometastatic (tumour deposits of size up to 2 mm in the greatest dimension) or macrometastatic (deposits more than 2 mm in size). Isolated tumour cells (ITCs) were defined as tumour foci measuring up to 0.2 mm. The frozen material as
Table 1 Clinicopathological characteristics of patients
Total Tumour grade Among patients with non-missing data Grade 1 Grade 2 Grade 3 Tumour size, mm Among patients with non-missing data T1a (≤5) T1b (>5–≤10) T1c (>10–≤20) T2 (>20–≤50) T3 (>50) Median (range) Lymphovascular involvement (LVI) Among patients with non-missing data Yes No Oestrogen receptor Among patients with non-missing data Positive Negative Progesterone receptor Among patients with non-missing data Positive Negative HER2 Among patients with non-missing data Positive Negative Histology Among records with non-missing data IDC ILC Mucinous Tubular Metaplastic Papillary Cribriform Medullary Neuroendocrine Apocrine Adenoid cystic Adenosquamous IDC and ILC IDC and Mucinous
No.
%
2202
100.0
2021 305 818 898
100.0 15.1 40.5 44.4
2069 68 183 741 973 104 22.0 (0.5–500.0)
100.0 3.3 8.8 35.8 47.0 5.0
2201 442 1759
100.0 20.1 79.9
1951 1495 456
100.0 76.6 23.4
1950 1384 566
100.0 71.0 29.0
1908 427 1481
100.0 22.4 77.6
2078 1801 98 65 30 5 22 13 11 2 2 1 1 22 5
100.0 86.7 4.7 3.1 1.4 0.2 1.1 0.6 0.5 0.1 0.1 0.1 0.1 1.1 0.2
well as any unfrozen SLN tissue were fixed and embedded in paraffin. Serial sections were stained with H&E and examined microscopically. Immunohistochemical (IHC) stains for CAM5.2 and AE1:AE3 were used only when the presence of cells suspicious of metastases were seen on H&E sections, needing IHC verification.
Statistical analysis Outcomes of the IFS of SLN were compared with that based on final histopathological analysis of the paraffin section of SLN for standard computation of FNR, sensitivity (Se), negative predictive value (NPR) and false NPR. False negative cases were defined as patients in whom a negative FS result was obtained, and whose final permanent paraffin section was positive. FNR was defined as (false negative)/(true positive+false negative). The sensitivity of IFS was defined as (true positive)/(true positive+false negative). Logistic regression models were fitted to estimate the ORs to assess the association of various variables with a false negative diagnosis of IFS of SLN. Multivariable analyses were performed on variables with p
