Prospective phase II trial of concomitant boost radiotherapy for stage II nasopharyngeal carcinoma

Stage II nasopharyngeal carcinoma (NPC) treated with conventionally fractionated radiotherapy results in suboptimal outcome. This report aims to document the outcome of Stage II NPC patients treated with external beam radiotherapy delivered using an accelerated concomitant boost (C-Boost) schedule. Forty-seven 1997 AJCC Stage II NPC patients were enrolled and analyzed in this prospective phase II clinical trial. The primary tumor and clinically involved nodes received a total dose of 72Gy in 42 fractions. C-Boost for gross disease consisted of 18Gy in 12 fractions commencing on day 19, and delivered at least 6h after the first dose. Patients were assessed for response, survival and toxicity. With a median follow-up of 30 months, 4 patients developed local recurrence only, 2 had persistent neck nodal disease or recurrence, and 1 with both locoregional recurrences. Distant metastases were seen in 5 patients, with or without locoregional recurrence. A total of 5 patients succumbed from nasopharyngeal cancer: four from effects of distant metastases and 1 from progressive local disease. The 3-year local, regional, and overall survival rates were 87.1%, 92%, and 85.9%, respectively. All patients experienced some degree of acute and/or late toxicity. Moderate to severe late toxicities (grade 3 and 4) were observed in 17% of cases. This C-Boost radiotherapy regimen administers a higher biologically effective dose compared with conventional radiation schedules. The local control after C-Boost radiation seems high for patients with stage II nasopharyngeal carcinoma, thus justifies further investigation to confirm its efficacy.