Should high-dose-rate brachytherapy boost be used in early nasopharyngeal carcinomas?

Abstract

Radiation with or without chemotherapy is the main treatment of nasopharyngeal carcinomas (NPC). Local recurrence is difficult to manage. Local control is dose-dependent. To analyze the effect of an endocavitary brachytherapy boost after external beam radiation (EBRT) to decrease local recurrence. Thirty patients with T0-T2 NPC were treated: 70% T1, 20% T2 and 10% T0; 33.3% N0, 20% N1, 43.3% N2 and 3.3% N3; 90% were undifferentiated carcinoma. All they received a 192-Ir high dose rate brachytherapy (HDR-BT) boost after 60 Gy of EBRT. The Rotterdam applicator was used in most cases, 3-4 fractions of 3.75-3 Gy in two days. With median follow-up (FU) of 63 months, a single parapharyngeal failure resulted in local control of 100% at 3 years and 95% at 5 years. Local control for T0-1 was 100% and for T2 67% at five years (p = 0.02). Regional-free recurrence survival was 92% at 5 years. Metastasis-free survival was 84% at 5 years. All cases of metastasis had histopathology of undifferentiated. The overall and cause-specific survival was 96% and 86% at 3 and 5 years. No late complications related to brachytherapy were described. A HDR-BT boost is useful to decrease the incidence of local recurrence of NPC to 5%. With a fractionated schedule of 3-4 fractions in two days, Rotterdam applicator and 3-D planning, no late complications are described. Therefore we recommend to use brachytherapy boost in all early NPC.