Volumetric analysis of tumor extent in nasopharyngeal carcinoma and correlation with treatment outcome.
OBJECTIVE
To investigate the variability of tumor volume in nasopharyngeal carcinoma using quantitative measurements of tumor bulk derived from computed tomography, and to study the prognostic value of tumor volume in comparison with other variables.


METHODS
Two hundred ninety patients with newly diagnosed nasopharyngeal carcinoma were included in the study. The primary tumor volume (PTV) and nodal tumor volume (NTV) were obtained by outlining the tumor contour followed by summation of areas in sequential pretreatment computed tomography axial scans. Total tumor volume (TTV) was obtained by adding the PTV and NTV. All patients had radiotherapy as the primary treatment, 67 patients also received cisplatin-based neoadjuvant chemotheraphy.


RESULTS
A large variation in tumor volume was observed, especially in advanced stage disease. The median PTV (cc) in Ho's T1, T2, and T3 disease were: 6.9 (range: 0.9-42.7), 18.8 (1.6-127.9), and 52.4 (3.3-166.8). The median TTV (cc) in Ho's stage I to IV disease were: 7.6 (range: 1.3-42.7), 19.8 (3.2-55.7), 40.7 (4.1-222.7), and 51.1 (3.1-274.7). Patients with a large PTV (>60 cc) were associated with significantly poorer local control (5-year local control rate: 56%) and disease-specific survival (5-year survival rate: 53%). In patients with a small PTV (< or =20 cc), there were no significant differences in local control among different T stages. Large NTV (>30 cc) was associated with significantly higher distant failure rate (5-year distant relapse-free survival rate: 54%) and lower disease-specific survival (5-year survival rate: 40%). In multivariate analysis, only PTV was found to be an independent factor in predicting local control.


CONCLUSIONS
A large variation of tumor volume was present in different T stage disease of nasopharyngeal carcinoma, and PTV represents an independent prognostic factor of local control that appears to be more predictive than Ho's T stage classification.
Chua
D T
DT
Department of Radiotherapy and Oncology, The University of Hong Kong, Queen Mary Hospital, Hong Kong.
Sham
J S
JS
Kwong
D L
DL
Tai
K S
KS
Wu
P M
PM
Lo
M
M
Yung
A
A
Choy
D
D
Leong
L
L
D000328:Adult; D000704:Analysis of Variance; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002277:Carcinoma / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy*; D017024:Chemotherapy, Adjuvant; D002945:Cisplatin / Q000008:administration & dosage; D019583:Dose Fractionation, Radiation; D015251:Epirubicin / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy*; D009367:Neoplasm Staging; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
D015251:Epirubicin; D002945:Cisplatin