In!. J. Radmrion Ono~lo~.v Btol Phys, Vol. Printed I” the U.S.A. All rights reserved.
19, pp.
I I7 I-I
0360~3016/90 $3.M) t .oO copyright0 1990 Pergarnon Press plc
175
0 Original Contribution COMPUTED
TOMOGRAPHY IN NASOPHARYNGEAL CARCINOMA: T-STAGE CONVERSION WITH CT-STAGING
PART I:
P. OLMI, M.D.,* E. CELLAI, M.D.,* A. CHIAVACCI, M.D.,* C. FALLAI, M.D.,* G. GIANNARDI,
M.D.,+
R. FARGNOLI,
M.D.+ AND N. VILLARI, M.D.+
University and Hospital, Florence Two hundred seventeen consecutive patients were treated with radiotherapy alone, with curative intent, from 1970 to 1985 at the Radiotherapy Unit of the University and Hospital of Florence. The distribution according to T and N staging with polytomography was compared to patients (106 out of 217) who had CT scans done at presentation. Tl cases were less frequent (6.6% vs 27%) in the CT-staged series, whereas T3 showed a higher incidence (30.2% vs 12.6%). The advantages of CT over conventional tomography were quantitated in a subset of 97 patients who underwent both staging procedures. Site-by-site, CT displayed a higher percentage of involvement than polytomography: parapharyngeal spread 18% vs 2%, oropharynx 16% vs 8%, choanae and nasal cavities 28% vs 13%, ethmoid and maxillary sinus 29% vs 13%. Information provided by CT caused a T-stage conversion in 23 out of 97 cases (23%): 4 out of 11 Tl, 16 out of 44 T2,3 out of 16 T3. Nasopharynx,
Neoplasms,
CT-staging.
INTRODUCTION
1978; the remaining 106 patients were accrued from December 1978. All patients underwent clinical staging with complete history, physical examination, and indirect and/ or direct inspection of nasopharynx; confirmatory biopsy was always obtained. Plain skull radiographs in the three standard views were taken for al1patients; in most patients a polytomographic examination was performed (207/ 2 16). From 1978, 106 patients had CT scans done at first presentation. Patients were positioned to produce standard axial views, with the gantry parallel to the Reid’s (orbitomeatal) line. Coronal sections were obtained with 60-80 obliquely incident beams-positioned as to the Reid’s plane. Initially, CT scans were carried out with a total body machine of second generation through 13 mm thick contiguous sections (6). From 1982, a third generation scanner became available and sections 6 mm thick were obtained: furthermore, coronal sections were more easily performed and scans were no longer jeopardized by artifacts due to dental fillings. Contrast enhancement was used in patients when intracranial extension was suspected. Intravenous contrast was injected with rapid drip infusion (5); generally, in these cases, scans 3 mm thick were used.
It is commonly agreed that no staging procedure of nasopharyngeal carcinoma (NPC) can be called exhaustive without CT-scanning (11, 23). Many papers have been published which focus on the normal anatomy of the nasopharynx and adjacent structures, problems of differential diagnosis, and malignant lesions imaging (4, 5, 9, 13, 16, 24, 25) but only a few authors have quantitated areas of gain for CT versus conventional staging (20, 32, 33). This study compares the distribution by T and N stage of an older series (group A), staged with conventional clinical and radiological methods, to the distribution observed in a more recent group of patients (group B), all of whom were submitted to CT before treatment. Furthermore, in a large subset of 97 patients of the more recent series in which both traditional and CT staging were performed, we investigated areas of improved imaging, particularly at the primary site, and CT-proved involved sites to determine change in T stage. METHODS
AND MATERIALS
Two hundred seventeen consecutive patients were treated with radiotherapy alone, with curative intent, from 1970 to 1985; the minimum follow-up was 3 years. One hundred eleven cases were irradiated before December * Department of Radiotherapy. +Imaging Department. Reprint requests to: P. Olmi, Unita’ di Radioterapia,
RESULTS The distribution by T and N stage according to the UICC Staging System (1978) (29) is reported in Tables 1 timento di Fisiopatologia Clinica, Universita’ di Firenze, v.le Morgagni, Careggi, 50 134 Firenze, Italy.
Dipar-
Accepted 1171
for publication
24 May 1990.
I. J. Radiation Oncology 0 Biology 0 Physics
1172
Table 1. Distribution according to T and N stage (non CTstaged patients)-UICC 1978
Tl T2 T3 T4 Total
NO (%)
Nl (%)
N2 (%)
N3 (%)
Tot. (%)
6 (5.4) 6 (5.4) 3 (2.7) 9 (8.1)
13 (11.7) 9 (8.1) 2 (1.8) 2 (1.8)
2 (1.9) 3 (2.7) 2 (1.8) 3 (2.7)
9 (8.1) 17 (15.3) 7 (6.3) 18 (16.2)
30 (27) 35 (31.5) 14 (12.6) 32 (28.8)
24 (21.6)
26 (23.4)
10 (9)
51 (45.9)
111
and 2. The incidence of nodal involvement appears similar; T 1 cases are definitely less frequent in the more recent series (6.6% vs 27%), whereas T3 shows a higher incidence
in group B (30.2%) than in group A (12.6%). Different information obtained with conventional and CT staging is shown in Table 3. In all sites CT displayed a higher percentage of involvement than suspected by clinical examination plus polytomographic information. The sensitivity of CT was especially higher in diagnosing parapharyngeal spread ( 18% vs 2% with conventional staging only); detection of involvement was doubled with regard to invasion of the oropharynx (16% vs 8%), choanae and nasal cavities (28% vs 13%), and ethmoid and maxillary sinuses (29% vs 13%). [Examples are shown in Figure 1.1 Three of 97 patients, initially NO, were considered Nl because of enlargement, observed by CT, of nodes difficult to palpate (retropharyngeal, deep cervical nodes). Two other patients with apparently homolateral adenopathy (Nl) were classified N2 (bilateral lymph nodes) following CT. Additional information provided by CT resulted in T-stage conversion in 23 out of 97 cases (23%) (Table 4). Upstaging only was observed: 4 out of 11 Tl (36%) and 16 out of 44 T2 (36%) were shifted to more advanced stages. Also 3 out of 16 T3 lesions were staged in the upper category after CT. The involvement of sites which determined a change in T stage are detailed in Table 5; spread to more than one contiguous structure was often revealed. DISCUSSION
AND CONCLUSIONS
The most striking feature of the distribution according to T and N stages in the group staged with CT(B), when compared to the conventionally staged group (A), is the reduction of apparently localized lesions (T 1). T 1 and T2 Table 2. Distribution according to T and N stage (CT-staged patients)-UICC 1978 NO (%)
Nl (W)
Tl T2 T3 T4
I (0.9) 5 (4.7) 4 (3.8) 17 (16)
2 (1.9) 10 (9.4) 7 (6.6) 4 (3.8)
-
Total
27 (25.5)
23 (21.7)
N2 (%)
N3 (%)
Tot. (%)
(-) 4 (3.8) 3 (2.8) 4 (3.8)
4 (3.8) 15 (14.2) 18 (17) 8 (7.5)
7 (6.6) 34 (32.1) 32 (30.2) 33 (31.1)
11 (10.4)
45 (42.5)
106
November 1990, Volume 19, Number 5
Table 3. Conventional
vs CT-staging of NPC: involved structures
Nasopharynx Upper/posterior wall Right lateral wall Left lateral wall Anterior spread Choanae Nasal fossae Maxillary sinus Ethmoid Orbit Lateral spread Parapharyngeal space (+ infratemporal fossa) Middle ear Pterygoyd plates Upper spread Sphenoid sinus Petrous apex Base of the skull Lower spread Oropharynx
Non-CT staged pts.
CT staged pts.
96 47 45
97 53 52 16 12 13 16 6
2 4 4
17 5 11
6 4 13
9 7 14
8
17
lesions, which amounted to 58.5% before the advent of CT, decreased to a far lower 38.7%. Whether these differences can be attributed to limitations in the conventional staging of NPC or to selection bias is difficult to determine with absolute certainty, especially in retrospect. However, one is lead to conclude that the CT substantially altered the incidence of early and advanced NPC’s. An indirect confirmation of this hypothesis might be obtained by comparing non-CT and CT staging of nasopharyngeal carcinoma in the same group of patients: in a subset of 97 patients, upstaging of limited lesions was observed in 36% of the cases. A higher shift (50%-52%) to more advanced stages was reported by [Zheng et al. (34)] Yamashita et al. (32) in Tl and T2 tumors of the nasopharynx. In the paper of Yu et al. (33), 6 of 11 T2 were upstaged. The incidence of change in T stage was lower in the T3 group and nil in T4 cases, both in our analysis and the aforementioned papers. Even if T4 cases are unlikely to have their stage changed by CT scan, this does not mean that the accurate evaluation of the disease extent is not important in the most advanced neoplasms in order to incorporate information in a more adequately tailored treatment volume (33). Our study, in agreement with Yamashita et al., Yu et al., and Nehen et al. (19, 32, 33), demonstrates the superiority of CT versus conventional clinical and radiological staging of NPC due to the capability of CT to display changes in both bones and soft tissues. We agree with Yu et al. (33) that CT scan has a unique ability to show the involvement of the parapharyngeal space which holds, in both studies, the leading place among the sites of extranasopharyngeal spread detected
NPC: CT-staging 0 P. OLMI et al.
1173
Fig. 1. Examples of T stage changes of NPCs after CT-staging. (a) Oropharyngeal extension (T-stage change: T2-T3); (b) Limited involvement of posterior nasal cavity (T-stage change: T2T3); (c) Erosion of the left petrous apex (T-stage change: T3T4); (d) Orbital invasion (T-stage change: T3-T4); (e) Orbital invasion, detail of the apex.
W
1174
I. J. RadiationOncology0 Biology0 Physics
November1990,Volume19,Number5
Table 4. CT vs Non-CT staging of NPC: distribution by T stage
Table 5. Conventional vs CT-staging of NPC: involved structures and T-stage conversion
CT-staged cases Non-CT staged cases
Tl
T2
T3
3 28
1 10 13
31
24
Tl T2 T3 T4
11 44 16 26
7
Total
97
7
T stage conversion
No. of Pts
T-stage modifying involved structures
No. involved*
Tl-T2 Tl-T3 T2-T3
3 1 10
T2-T4
6
T3-T4
3
Lateral wall Oropharynx Parapharyngeal space Oropharynx Choanae Pterygoid plates Ethmoid Sphenoid sinuses Sphenoid bone Maxillary sinuses Maxillary sinuses Ethmoid
3 1 7 4 3 3 2 2 1 2 2
Pterygoid plates
1 1
T4 6 3 26 35
by CT. Note, however, that according to Yamashita et al. (32) whether that space, often deformed, is actually invaded or merely compressed by the tumor can not be diagnosed from CT findings. Incidentally, in their analysis, definite invasion into the infratemporal fossa was rare. Similarly, in our study the term “parapharyngeal space” includes only a few cases in which a contemporaneous extension into the adjacent infratemporal fossa was observed. Involvement of the choanal plane by NPC is relatively often encountered, whereas extensive spreading to nasal cavities is not showed: our data partially confirm previous results of Yamashita et al. (32). On the other hand, in our study, CT revealed oropharyngeal extension in a higher percent of cases than previously suspected with conventional staging; submucosal spread patterns could explain why lesions were not evident by simple physical examination as stated by others (32). Bony erosion of the base of skull notoriously occurs by direct extension of the primary lesion in the nasopharynx; CT is probably the only radiological way to show the continuous intracranial invasion ( 19). CT shows higher sensitivity than polytomography (32, 33) revealing site and extent of even subtle bone destruction. Once more, our data support the previous reports and stress that “CT scanning plays a vital role in the assessment of the extent of tumors affecting the skull base” (22). The information provided by CT determined a change in T stage in 23 out of 97 cases. The primary volume was enlarged according to the CT findings in 14 cases. The upper margin was raised to cover endocranial extent or lowered to include oropharyngeal spread, whereas the treatment technique was not changed. In nine cases with anterior spread, the “standard” two lateral opposed field technique was modified, and a three-field technique was adopted. An alternative method of tumor localization, magnetic resonance imaging (MRI), is under evaluation. Several authors (1, 2, 7, 26, 28) reported on its exquisite ability
Orbital floor
I
* Some patients showed more than one involved site. in defining disease extent. Other recent reports (14, 2 1, 30, 3 1) support its growing role in diagnostic strategy of head and neck cancers. From 1985 we staged 23 patients affected by NPC with both MRI and CT (10). With regard to the primary extent, information was grossly equivalent, whereas in his study (3), Curran reported several alterations in field margins dictated by MRI as compared to the margins dictated by CT findings. The impact of CT on lymph node staging is reported by Mancuso et al. (15, 17) but we feel that the high incidence of clinically evident adenopathies at presentation weakens the contribution of the CT. Furthermore, enlargement alone may be a misleading parameter (18), due to the lack of specificity (15); in fact, benign reactive hyperplasia may simulate malignant enlargement. Necrosis also is used as criterion of malignancy; however, lucent foci in normal-sized nodes can be represented by partial fat replacement (17). MRI gives excellent results with abnormal lymph nodes, equivalent to and probably better than CT (8, 2 1, 27). We found deep not palpable adenopathies, which were not shown on CT, in 3 out of 23 cases of NPC staged with both modalities ( 10); in 3 additional cases MRI clearly distinguished nodes from the primary which they were strictly adjacent to. It should be pointed out that false positive errors related to reactive lymphadenitis are possible (12). Of note, Gd-DTPA was not available. Currently, we stage patients affected by NPC with both CT and MRI. In our opinion, the role of CT versus MRI is still under investigation and no firm conclusions can be established yet.
REFERENCES 1. Braun, I. F. MRI of the nasopharynx. Radiol. Clin. N. Am.
27:3 15-330; 1989. 2. Carter, B. L.; Runge, V. S. Imaging modalities for the study
of the pamnasal sinusesand nasopharynx. Otolaryngol. Clin. N. Am. 21:395-420; 1988. 3. Curran, W. P.; Hackney, D. B.; Blitzer, P. H.; Bilaniuk, L.
NPC: CT-staging 0 P. OLMI et al.
4.
5.
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The value of magnetic resonance imaging of the nasopharynx. Int. J. Radiat. Oncol. Biol. Phys. 12:2 189-2 196; 1986. Curtin, H. D. Nasopharynx and paranasopharyngeal space. In Latchaw, R. E., ed. CT of the head, neck and spine. Chicago: Year Book Medical Publisher; 198555 l-56 1. Dal Pozzo, G.; De Dominicis, R.; Nori, A.; Nori-Bufalini, G.; Menichelli, F.; Pasquini, U.; Perugini, S.; Salvolini, U. Criteri diagnostici tomodensitometrici nella patologia neoplastica dei seni paranasali e della rinofaringe. Radiol. Med. 67:97-108; 1981. Dal Pozzo, G.; Villari, N.; Masi, A. La TC nell’ anatomica e patologia neoplastica della faringe. It. Curr. Rad. 1: 1518; 1982. Dillon, W. P.; Mills, C. M.; Kios, B.; De Groot, J.; BrantZawadzki, M. Magnetic resonance imaging of the nasopharynx. Radiology 152:73 l-738; 1984. Dooms, G. C.; Hricak, H.; Crooks, L. E.; Higgins, C. B. Magnetic resonance imaging of the lymph nodes: comparison with CT. Radiology 153:7 19-728; 1984. Doubleday, L. C.; Jing, B.; Wallace, S. Computed tomography of the infratemporal fossa. Radiology 138:6 19-624; 1981. Giannardi, G.; Fargnoli, R.; Villari, N. Diagnostica per immagini. In: Alajmo, E., ed. 11carcinoma rinofaringeo. Pisa: Pacini Editore; 1989:75-105. Griem, M. L.; Chiang, D. T. C. Nasopharynx. In: Laramore, G. E., Ed. Radiation therapy of head and neck cancer. Berlin: Springer-Verlag; 1989:89-105. Heppt, W.; Haels, J.; Lenarz, T.; Mende, U.; Gademann, C. Detection and assessment of cervical lymph node metastases in head and neck tumors. A comparison of methods. Laryngorhinootologie 68:327-332; 1989. Hoover, L. A.; Hanafee, W. N. Differential diagnosis of nasopharyngeal tumors by computed tomography scanning. Arch. Otolaryngol. 109:43-47; 1983. Mafee, M. F.; Campos, M.; Raju, S.; Samett, E.; Mohamadi, H.; Sadighi, S.; Heffez, L.; Friedman, M.; Chow, J. M. Head and neck: high field magnetic resonance imaging versus computed tomography. Otolaryngol. Clin. N. Am. 2 1:5 13546: 1988. Mancuso, A. Cervical lymph node metastases: oncologic imaging and diagnosis. Int. J. Radiat. Oncol. Biol. Phys. 10: 41 l-423; 1984. Mancuso, A.; Bohman, L.; Hanafee, W.; Maxwell, D. Computed tomography of the nasopharynx: normal and variants of normal. Radiology 137: 113-121; 1980. Mancuso, A.; Hamsberger, H. R.; Muraki, A. S.; Stevens, M. Computed tomography of cervical and retropharyngeal lymph nodes: normal anatomy, variants of normal, and applications in staging head and neck cancer: I. Normal anatomy. Il. Pathology. Radiology 148:709-723; 1983. McGavran, M. H.; Bauer, W. C.; Ogura, J. H. The incidence of cervical lymph node metastases from epidermoid carcinoma of the larynx and the relationship to certain characteristics of the primary tumor. Cancer 14:55-66; 196 1.
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19. Nehen, A. M.; Illum, P.; Ratjen, E.; Illum, F.; Elbrond, 0. Computed tomography and nasopharynx. Acta Radiol. Diag. 22:285-287; 198 1. 20. Olmi, P.; Casamassima, F.; Cellai, E.; Chiavacci, A.; Dini, C.; Fargnoli, R. Ruolo della tomografia assiale computerizzata nello studio delle neoplasie rinofaringee. In: Radiologia, Vol. III. Bologna: Monduzzi; 1984:394-398. 21. O’Reilly, B. J.; Leung, A.; Greco, A. Magnetic resonance imaging in head and neck cancer. Clin. Otolaryngol. 14: 67-68; 1989. 22. Parsons, C. Computed tomography of the skull base. In: Bloom, H. J. G.; Hanham, I. W. F.; Shaw, H. J. Head and neck oncology. New York: Raven Press: 1987: 137- 150. 23. Shuman, W. P.; Moss, A. A. Imaging studies in head and neck cancer. In: Laramore, G. E., ed. Radiation therapy of head and neck cancer. Berlin: Springer-Verlag; 1989: 13-26. 24. Silver, A. J.; Mawad, M. E.; Hilal, S. K.; Sane, P.; Ganti, S. R. Computed tomography of the nasopharynx and related spaces: 1. Anatomy. Radiology 147:725-731; 1983. 25. Silver, A. J.; Mawad, M. E.; Hilal, S. K.; Sane, P.; Ganti, S. R. Computed tomography of the nasopharynx and related spaces: pathology. Radiology 147:733-738; 1983. 26. Som, P. M.; Braun, I. F.; Shapiro, M. D.; Reede, D. L.; Curtin, N. D.; Zimmerman, R. A. Tumors of the parapharyngeal space and upper neck: MR imaging characteristics. Radiology 164:823-829: 1927. 27. Stark, D.; Moss, A.; Gamsu, G.; Clark, 0. H.; Gooding, G. A.; Webb, W. R. Magnetic resonance imaging of the neck. Radiology 150:455-46 1; 1984. 28. Teresi, L. M.; Lulkin, R. B.; Vinuela, F.; Dietrich, R. B.; Wilson, G. H.; Bentson, J. R.; Hanafee, W. N. MR imaging of the nasopharynx and floor of the middle cranial fossa. Part II: malignant tumors. Radiology 164:8 17-82 1; 1987. 29. Union lntemationale Contre le Cancer (UICC). TNM: classification des tumeurs malignes. Geneve: UICC; 1978:2732. 30. Vogl, T. Diseases of the aerodigestive tract and of the soft tissues of the neck. Comparison of MRI and CT. Rontgenblatter 42: 199-209; 1989. 3 1. Vogl, T.; Dresel, S.; Schedel, H.; Markl, A.; Grevers, G.; Stelzer, S.; Lissner, J. MRI of the nasopharynx with GdDTPA: its value and differential diagnostic criteria. Rofo. 150:516-522; 1989. 32. Yamashita, S.; Kondo, M.; Hashimoto, S. Conversion of T-stages of nasopharyngeal carcinoma by computed tomography. Int. J. Radiat. Oncol. Biol. Phys. 11: 1017-1021; 1985. 33. Yu, Z.; Xu, G.; Huang, Y.; Hu, Y.; Su, X.; Gu, X. Value of computed tomography in staging the primary lesion (Tstaging) of nasopharyngeal carcinoma (NPC): An analysis of 54 patients with special reference to the parapharyngeal space. Int. J. Radiat. Oncol. Biol. Phys. 11:2143-2147; 1985. 34. Zheng, G. V.; Zeng, Q. X.; Wu, P. H.: Chen, C. Q. Computerized tomography in clinical staging of nasopharyngeal carcinoma. Chinese J. Cancer 6:5-7: 1986.
19, pp.
I I7 I-I
0360~3016/90 $3.M) t .oO copyright0 1990 Pergarnon Press plc
175
0 Original Contribution COMPUTED
TOMOGRAPHY IN NASOPHARYNGEAL CARCINOMA: T-STAGE CONVERSION WITH CT-STAGING
PART I:
P. OLMI, M.D.,* E. CELLAI, M.D.,* A. CHIAVACCI, M.D.,* C. FALLAI, M.D.,* G. GIANNARDI,
M.D.,+
R. FARGNOLI,
M.D.+ AND N. VILLARI, M.D.+
University and Hospital, Florence Two hundred seventeen consecutive patients were treated with radiotherapy alone, with curative intent, from 1970 to 1985 at the Radiotherapy Unit of the University and Hospital of Florence. The distribution according to T and N staging with polytomography was compared to patients (106 out of 217) who had CT scans done at presentation. Tl cases were less frequent (6.6% vs 27%) in the CT-staged series, whereas T3 showed a higher incidence (30.2% vs 12.6%). The advantages of CT over conventional tomography were quantitated in a subset of 97 patients who underwent both staging procedures. Site-by-site, CT displayed a higher percentage of involvement than polytomography: parapharyngeal spread 18% vs 2%, oropharynx 16% vs 8%, choanae and nasal cavities 28% vs 13%, ethmoid and maxillary sinus 29% vs 13%. Information provided by CT caused a T-stage conversion in 23 out of 97 cases (23%): 4 out of 11 Tl, 16 out of 44 T2,3 out of 16 T3. Nasopharynx,
Neoplasms,
CT-staging.
INTRODUCTION
1978; the remaining 106 patients were accrued from December 1978. All patients underwent clinical staging with complete history, physical examination, and indirect and/ or direct inspection of nasopharynx; confirmatory biopsy was always obtained. Plain skull radiographs in the three standard views were taken for al1patients; in most patients a polytomographic examination was performed (207/ 2 16). From 1978, 106 patients had CT scans done at first presentation. Patients were positioned to produce standard axial views, with the gantry parallel to the Reid’s (orbitomeatal) line. Coronal sections were obtained with 60-80 obliquely incident beams-positioned as to the Reid’s plane. Initially, CT scans were carried out with a total body machine of second generation through 13 mm thick contiguous sections (6). From 1982, a third generation scanner became available and sections 6 mm thick were obtained: furthermore, coronal sections were more easily performed and scans were no longer jeopardized by artifacts due to dental fillings. Contrast enhancement was used in patients when intracranial extension was suspected. Intravenous contrast was injected with rapid drip infusion (5); generally, in these cases, scans 3 mm thick were used.
It is commonly agreed that no staging procedure of nasopharyngeal carcinoma (NPC) can be called exhaustive without CT-scanning (11, 23). Many papers have been published which focus on the normal anatomy of the nasopharynx and adjacent structures, problems of differential diagnosis, and malignant lesions imaging (4, 5, 9, 13, 16, 24, 25) but only a few authors have quantitated areas of gain for CT versus conventional staging (20, 32, 33). This study compares the distribution by T and N stage of an older series (group A), staged with conventional clinical and radiological methods, to the distribution observed in a more recent group of patients (group B), all of whom were submitted to CT before treatment. Furthermore, in a large subset of 97 patients of the more recent series in which both traditional and CT staging were performed, we investigated areas of improved imaging, particularly at the primary site, and CT-proved involved sites to determine change in T stage. METHODS
AND MATERIALS
Two hundred seventeen consecutive patients were treated with radiotherapy alone, with curative intent, from 1970 to 1985; the minimum follow-up was 3 years. One hundred eleven cases were irradiated before December * Department of Radiotherapy. +Imaging Department. Reprint requests to: P. Olmi, Unita’ di Radioterapia,
RESULTS The distribution by T and N stage according to the UICC Staging System (1978) (29) is reported in Tables 1 timento di Fisiopatologia Clinica, Universita’ di Firenze, v.le Morgagni, Careggi, 50 134 Firenze, Italy.
Dipar-
Accepted 1171
for publication
24 May 1990.
I. J. Radiation Oncology 0 Biology 0 Physics
1172
Table 1. Distribution according to T and N stage (non CTstaged patients)-UICC 1978
Tl T2 T3 T4 Total
NO (%)
Nl (%)
N2 (%)
N3 (%)
Tot. (%)
6 (5.4) 6 (5.4) 3 (2.7) 9 (8.1)
13 (11.7) 9 (8.1) 2 (1.8) 2 (1.8)
2 (1.9) 3 (2.7) 2 (1.8) 3 (2.7)
9 (8.1) 17 (15.3) 7 (6.3) 18 (16.2)
30 (27) 35 (31.5) 14 (12.6) 32 (28.8)
24 (21.6)
26 (23.4)
10 (9)
51 (45.9)
111
and 2. The incidence of nodal involvement appears similar; T 1 cases are definitely less frequent in the more recent series (6.6% vs 27%), whereas T3 shows a higher incidence
in group B (30.2%) than in group A (12.6%). Different information obtained with conventional and CT staging is shown in Table 3. In all sites CT displayed a higher percentage of involvement than suspected by clinical examination plus polytomographic information. The sensitivity of CT was especially higher in diagnosing parapharyngeal spread ( 18% vs 2% with conventional staging only); detection of involvement was doubled with regard to invasion of the oropharynx (16% vs 8%), choanae and nasal cavities (28% vs 13%), and ethmoid and maxillary sinuses (29% vs 13%). [Examples are shown in Figure 1.1 Three of 97 patients, initially NO, were considered Nl because of enlargement, observed by CT, of nodes difficult to palpate (retropharyngeal, deep cervical nodes). Two other patients with apparently homolateral adenopathy (Nl) were classified N2 (bilateral lymph nodes) following CT. Additional information provided by CT resulted in T-stage conversion in 23 out of 97 cases (23%) (Table 4). Upstaging only was observed: 4 out of 11 Tl (36%) and 16 out of 44 T2 (36%) were shifted to more advanced stages. Also 3 out of 16 T3 lesions were staged in the upper category after CT. The involvement of sites which determined a change in T stage are detailed in Table 5; spread to more than one contiguous structure was often revealed. DISCUSSION
AND CONCLUSIONS
The most striking feature of the distribution according to T and N stages in the group staged with CT(B), when compared to the conventionally staged group (A), is the reduction of apparently localized lesions (T 1). T 1 and T2 Table 2. Distribution according to T and N stage (CT-staged patients)-UICC 1978 NO (%)
Nl (W)
Tl T2 T3 T4
I (0.9) 5 (4.7) 4 (3.8) 17 (16)
2 (1.9) 10 (9.4) 7 (6.6) 4 (3.8)
-
Total
27 (25.5)
23 (21.7)
N2 (%)
N3 (%)
Tot. (%)
(-) 4 (3.8) 3 (2.8) 4 (3.8)
4 (3.8) 15 (14.2) 18 (17) 8 (7.5)
7 (6.6) 34 (32.1) 32 (30.2) 33 (31.1)
11 (10.4)
45 (42.5)
106
November 1990, Volume 19, Number 5
Table 3. Conventional
vs CT-staging of NPC: involved structures
Nasopharynx Upper/posterior wall Right lateral wall Left lateral wall Anterior spread Choanae Nasal fossae Maxillary sinus Ethmoid Orbit Lateral spread Parapharyngeal space (+ infratemporal fossa) Middle ear Pterygoyd plates Upper spread Sphenoid sinus Petrous apex Base of the skull Lower spread Oropharynx
Non-CT staged pts.
CT staged pts.
96 47 45
97 53 52 16 12 13 16 6
2 4 4
17 5 11
6 4 13
9 7 14
8
17
lesions, which amounted to 58.5% before the advent of CT, decreased to a far lower 38.7%. Whether these differences can be attributed to limitations in the conventional staging of NPC or to selection bias is difficult to determine with absolute certainty, especially in retrospect. However, one is lead to conclude that the CT substantially altered the incidence of early and advanced NPC’s. An indirect confirmation of this hypothesis might be obtained by comparing non-CT and CT staging of nasopharyngeal carcinoma in the same group of patients: in a subset of 97 patients, upstaging of limited lesions was observed in 36% of the cases. A higher shift (50%-52%) to more advanced stages was reported by [Zheng et al. (34)] Yamashita et al. (32) in Tl and T2 tumors of the nasopharynx. In the paper of Yu et al. (33), 6 of 11 T2 were upstaged. The incidence of change in T stage was lower in the T3 group and nil in T4 cases, both in our analysis and the aforementioned papers. Even if T4 cases are unlikely to have their stage changed by CT scan, this does not mean that the accurate evaluation of the disease extent is not important in the most advanced neoplasms in order to incorporate information in a more adequately tailored treatment volume (33). Our study, in agreement with Yamashita et al., Yu et al., and Nehen et al. (19, 32, 33), demonstrates the superiority of CT versus conventional clinical and radiological staging of NPC due to the capability of CT to display changes in both bones and soft tissues. We agree with Yu et al. (33) that CT scan has a unique ability to show the involvement of the parapharyngeal space which holds, in both studies, the leading place among the sites of extranasopharyngeal spread detected
NPC: CT-staging 0 P. OLMI et al.
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Fig. 1. Examples of T stage changes of NPCs after CT-staging. (a) Oropharyngeal extension (T-stage change: T2-T3); (b) Limited involvement of posterior nasal cavity (T-stage change: T2T3); (c) Erosion of the left petrous apex (T-stage change: T3T4); (d) Orbital invasion (T-stage change: T3-T4); (e) Orbital invasion, detail of the apex.
W
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I. J. RadiationOncology0 Biology0 Physics
November1990,Volume19,Number5
Table 4. CT vs Non-CT staging of NPC: distribution by T stage
Table 5. Conventional vs CT-staging of NPC: involved structures and T-stage conversion
CT-staged cases Non-CT staged cases
Tl
T2
T3
3 28
1 10 13
31
24
Tl T2 T3 T4
11 44 16 26
7
Total
97
7
T stage conversion
No. of Pts
T-stage modifying involved structures
No. involved*
Tl-T2 Tl-T3 T2-T3
3 1 10
T2-T4
6
T3-T4
3
Lateral wall Oropharynx Parapharyngeal space Oropharynx Choanae Pterygoid plates Ethmoid Sphenoid sinuses Sphenoid bone Maxillary sinuses Maxillary sinuses Ethmoid
3 1 7 4 3 3 2 2 1 2 2
Pterygoid plates
1 1
T4 6 3 26 35
by CT. Note, however, that according to Yamashita et al. (32) whether that space, often deformed, is actually invaded or merely compressed by the tumor can not be diagnosed from CT findings. Incidentally, in their analysis, definite invasion into the infratemporal fossa was rare. Similarly, in our study the term “parapharyngeal space” includes only a few cases in which a contemporaneous extension into the adjacent infratemporal fossa was observed. Involvement of the choanal plane by NPC is relatively often encountered, whereas extensive spreading to nasal cavities is not showed: our data partially confirm previous results of Yamashita et al. (32). On the other hand, in our study, CT revealed oropharyngeal extension in a higher percent of cases than previously suspected with conventional staging; submucosal spread patterns could explain why lesions were not evident by simple physical examination as stated by others (32). Bony erosion of the base of skull notoriously occurs by direct extension of the primary lesion in the nasopharynx; CT is probably the only radiological way to show the continuous intracranial invasion ( 19). CT shows higher sensitivity than polytomography (32, 33) revealing site and extent of even subtle bone destruction. Once more, our data support the previous reports and stress that “CT scanning plays a vital role in the assessment of the extent of tumors affecting the skull base” (22). The information provided by CT determined a change in T stage in 23 out of 97 cases. The primary volume was enlarged according to the CT findings in 14 cases. The upper margin was raised to cover endocranial extent or lowered to include oropharyngeal spread, whereas the treatment technique was not changed. In nine cases with anterior spread, the “standard” two lateral opposed field technique was modified, and a three-field technique was adopted. An alternative method of tumor localization, magnetic resonance imaging (MRI), is under evaluation. Several authors (1, 2, 7, 26, 28) reported on its exquisite ability
Orbital floor
I
* Some patients showed more than one involved site. in defining disease extent. Other recent reports (14, 2 1, 30, 3 1) support its growing role in diagnostic strategy of head and neck cancers. From 1985 we staged 23 patients affected by NPC with both MRI and CT (10). With regard to the primary extent, information was grossly equivalent, whereas in his study (3), Curran reported several alterations in field margins dictated by MRI as compared to the margins dictated by CT findings. The impact of CT on lymph node staging is reported by Mancuso et al. (15, 17) but we feel that the high incidence of clinically evident adenopathies at presentation weakens the contribution of the CT. Furthermore, enlargement alone may be a misleading parameter (18), due to the lack of specificity (15); in fact, benign reactive hyperplasia may simulate malignant enlargement. Necrosis also is used as criterion of malignancy; however, lucent foci in normal-sized nodes can be represented by partial fat replacement (17). MRI gives excellent results with abnormal lymph nodes, equivalent to and probably better than CT (8, 2 1, 27). We found deep not palpable adenopathies, which were not shown on CT, in 3 out of 23 cases of NPC staged with both modalities ( 10); in 3 additional cases MRI clearly distinguished nodes from the primary which they were strictly adjacent to. It should be pointed out that false positive errors related to reactive lymphadenitis are possible (12). Of note, Gd-DTPA was not available. Currently, we stage patients affected by NPC with both CT and MRI. In our opinion, the role of CT versus MRI is still under investigation and no firm conclusions can be established yet.
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