Adjuvant high-dose-rate brachytherapy after external beam radiotherapy in nasopharyngeal carcinoma.

PURPOSE

To compare the local control and survival rates obtained with either external beam radiation therapy (ERT) and adjuvant high-dose-rate (HDR) brachytherapy (BRT) or ERT alone in patients with nasopharyngeal cancer.

METHODS AND MATERIALS

Between December 1993 and December 1999, 144 patients (106 male, 38 female) with the diagnosis of nasopharyngeal cancer were treated with either ERT and adjuvant HDR BRT (Group A) or ERT alone (Group B) at our department. BRT was not applied in 38 patients for the following reasons: (1) Unit was unavailable (n = 13), (2) Patient was younger than 18 years (n = 17), (3) Patient received accelerated hyperfractionated ERT (n = 6), and (4) Patient refused BRT (n = 2). The median age for whole group was 43 (range: 9-82 years). According to the AJCC-1997 staging system, there were 11 (7.6%), 35 (24.3%), 38 (26.4%), and 60 (41.7%) patients in Stage I, II, III, and IV, respectively. There were 57 (39.6%) patients with T1, 41 (28.5%) with T2, 20 (13.9%) with T3, and 26 (18.1%) with T4 tumors. Histopathologic diagnosis was WHO 2-3 in 137 (95.2%) patients. ERT doses ranged between 58.8 and 74 Gy (median: 66 Gy). There were significantly more patients with young age, N2 status, and Stage III disease in Group B and with Stage II disease in Group A. Significantly more patients received chemotherapy in Group B. BRT with an HDR 192Ir microSelectron afterloading unit was delivered in 106 patients at the conclusion of ERT using a single-channel nasal applicator. Dose was prescribed at 1 cm from the source, and total dose of 12 Gy in 3 fractions on 3 consecutive days was given immediately after ERT. Besides radiotherapy, 82 (56.9%) patients received cisplatin-based chemotherapy, as well. Follow-up time ranged between 12 and 80 months (median: 32 months).

RESULTS

The two groups were comparable in terms of local recurrence, locoregional failure, regional failure, and rate of distant metastasis. Local failure was observed in 11 (10.3%) out of 106 patients in Group A and in 2 (5.2%) out of 38 patients in Group B (p > 0.05). Three-year disease-free survival rate was 67% and 80% (p = 0.07), respectively, and 3-year local recurrence-free survival rate was 86% and 94% (p = 0.23) for Group A and B, respectively. Multivariate analysis showed that advanced nodal status and male gender were significantly unfavorable factors for disease-free survival, and Stage II disease was unfavorable for local recurrence-free survival. The administration of adjuvant HDR BRT was not an independent prognostic factor in multivariate analysis. Out of 106 patients, 42 (39.7%) experienced nasal congestion, transient nasal obstruction, and/or fibrinous exudate in response to antihistaminic treatment. Only three (2.8%) patients experienced nasal synechy related, most probably, to the BRT. Five patients developed severe neural complications; only one out of five was observed in Group A. No severe complication attributed directly to BRT was detected.

CONCLUSION

The acute and late morbidity of adjuvant HDR BRT is acceptable with our treatment scheme, but we did not find any local control difference between our patients treated with adjuvant BRT after ERT and ERT alone. We believe that the exact role of adjuvant HDR BRT can be elucidated only by prospective randomized studies.