Local control, survival, and late toxicities of locally advanced nasopharyngeal carcinoma treated by simultaneous modulated accelerated radiotherapy combined with cisplatin concurrent chemotherapy: long-term results of a phase 2 study

Abstract

Background: The aim of this phase 2 study was to determine the long-term local control, survival, and late toxicities among patients with locally advanced nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT) with the simultaneous modulated accelerated radiation therapy (SMART) boost technique and concurrent chemotherapy.

Methods: Eighty-one patients with pathologically diagnosed locally advanced NPC were enrolled in this study. IMRT was delivered with the SMART boost technique at prescribed doses of 68 grays (Gy)/30 fraction to the nasopharynx gross target volume. Concurrent cisplatin chemotherapy (80 mg/m(2) /d on Days 1 and 22) was administered.

Results: The mean actual physical dose delivered to the nasopharynx gross target volume was 73.8 Gy, and the mean biologically effective dose (BED) for the nasopharynx gross target volume was 84.8 Gy. With a median follow-up of 54 months, 4 (4.9%) patients experienced local recurrence. The 5-year local control rate was 94.9%. Eighteen patients died. Among them, 66.7% died of distant metastasis. The 5-year disease-free and overall survivals were 76.7% and 74.5%, respectively. The most common late toxicities among 68 patients with ≥4 years follow-up were grade 1-2 xerostomia, hearing loss, skin dystrophy, and subcutaneous fibrosis. No grade 4 late toxicities were noted.

Conclusions: IMRT with SMART to enhance BED and concurrent chemotherapy is feasible in patients with locally advanced NPC. Long-term results showed excellent local control with fewer late toxicities, although no further improvement was noted in overall survival, and the major cause of death was distant metastasis. Exploration of more effective combined chemoradiation strategies is warranted.