ABSTRACT: BACKGROUND:We aimed to improve the outcomes for locoregionally advanced nasopharyngeal carcinoma by testing the feasibility and safety of the addition of bevacizumab to chemoradiotherapy. METHODS:We enrolled patients older than 18 years with stage IIB-IVB nasopharyngeal carcinoma from 19 centres in North America and Hong Kong. Treatment consisted of three cycles of bevacizumab (15 mg/kg) and cisplatin (100 mg/m(2)) both given on days 1, 22, and 43 of radiation (70 Gy) with intensity-modulated radiation therapy delivered over 33 days on a daily basis, Monday through Friday. Patients then received three cycles of bevacizumab (15 mg/kg) and cisplatin (80 mg/m(2)), both given on days 64, 85, and 106 after radiation, and three cycles of fluorouracil (1000 mg/m(2) per day), given on days 64-67, 85-88, and 106-109 after radiation. The primary endpoint was the occurrence of treatment-related grade 4 haemorrhage or any grade 5 adverse event in the first year. Analyses were done with all eligible patients who started protocol treatment. The trial is registered at ClinicalTrials.gov, number NCT00408694. FINDINGS:From Dec 13, 2006, to Feb 5, 2009, we enrolled 46 patients, of whom 44 were eligible for analysis. We recorded no grade 3-4 haemorrhages or grade 5 adverse events; nine patients (20%) had a treatment-related grade 1-2 haemorrhage. Nine patients had one or more grade 4 blood or bone marrow-related complication (grade 4 leucopenia was noted in six patients, grade 4 lymphopenia in five, grade 4 neutrophils in five, and grade 4 anaemia in one). One patient had two grade 4 infections with grade 3-4 neutrophils. One patient reported grade 4 tinnitus, one patient reported grade 4 thrombosis, one reported grade 4 radiation mucositis, and two reported grade 4 pharyngolaryngeal pain. With a median follow-up of 2·5 years (IQR 2·1-2·9), the estimated 2 year locoregional progression-free interval was 83·7% (95% CI 72·6-94·9), the 2 year distant metastasis-free interval was 90·8% (82·2-99·5), the 2 year progression-free survival was 74·7% (61·8-87·6), and 2 year overall survival was 90·9% (82·3-99·4). INTERPRETATION:The addition of bevacizumab to standard chemoradiation treatment for patients with nasopharyngeal carcinoma is feasible, and might delay the progression of subclinical distant disease. FUNDING:National Cancer Institute, USA.