RESUMO
PURPOSE: We previously reported our preliminary experience with nasopharyngeal cancer boosted after 60-70 Gy external beam radiotherapy (EBRT) by fractionated endocavitary brachytherapy (ECBT) to cumulative doses of 78-82 Gy. As for Stage III-IVB disease, cisplatin (CDDP)-based neoadjuvant chemotherapy (CHT) was given. The aim of the present study was to define the role of ECBT more accurately. METHODS AND MATERIALS: Ninety-one patients with primary nasopharyngeal cancer, staged according to the 1997 UICC/AJCC classification system, were treated between 1991 and 2000 with 60-70 Gy external beam radiotherapy and 11-18 Gy ECBT. Of the 91 patients, 21 were treated in conjunction with CHT and 70 without CHT. Tumors were subdivided into undifferentiated (UD) and well, moderately, and poorly differentiated (WMP-D) subtypes. Treatment results were analyzed for local control (LC), disease-free survival (DFS), freedom from distant metastasis, and overall survival (OS). RESULTS: A univariate and multivariate Cox regression analysis found stage, treatment period, age, and grade significant for LC, DFS, and OS. At 2 years, for Stage I-IIB (1st period, 1991-1996), the LC, DFS, and OS were 96%, 88%, and 80%, respectively, vs. 65%, 46%, and 52% for Stage III-IVB. For the 2nd treatment period (1996-2000; CHT for Stage III-IVB), the LC, DFS, and OS at 2 years was 100%, 90%, and 61% (Stage I-IIB), respectively, vs. 86%, 74%, and 66% (Stage III-IVB). Three prognostic groups (PGs) were constructed. For the 1991-1996 period, at 2 years, patients in the good PG (UD Stage I-IIB disease) had 100% LC and 92% OS; those in the intermediate PG (UD Stage III-IVB or WMP-D Stage I-IIB), had 94% LC and 71% OS; and those in the poor PG (WMP-D Stage III-IVB) had 47% LC and 40% OS. For the 1996-2000 period, at 2 years, the good PG had 100% LC and 88% OS; the intermediate PG had 100% LC and 64% OS; and the poor PG had 71% LC and 60% OS. CONCLUSION: For Stage I-IIB disease treated between 1991 and 2000, at 3 years, the LC and OS was 97% and 67%, respectively. The results with 77-81 Gy without CHT warrant EBRT combined with ECBT to remain our standard of care for Stage I-IIB disease. For N2-3 and/or T3-4 tumors, in addition to high doses of RT, neoadjuvant CHT was administered as of 1996. For the 1991-2000 period, at 3 years, the LC was 86% and the OS was 72% with CHT, with little extra morbidity; they were 68% and 35% without CHT. Because of better target coverage and sparing, T3-4 tumors are currently boosted by stereotactic RT to 81.2 Gy.