A phase I study of concurrent chemoradiotherapy with S-1 for T2N0 glottic carcinoma

Chemoradiation based on S-1, a novel oral antitumor agent of fluorinated pyrimidines, is the treatment for T2N0 glottic carcinoma; however, the optimal scheduling and dosing have still not been established. A phase I study was conducted to determine the maximum tolerated dose of S-1 with radiotherapy of 2 Gy/day for 5 days a week to a total dose of 60 Gy. Endpoints of this study were to examine the toxicity profile of this regimen and to determine the recommended dose of S-1.

Concomitant administration with the above-mentioned radiotherapy of S-1 once a day for 2 weeks, beginning on the day therapy was started, followed by 2 weeks off the drug and 2 weeks on the drug with the dose escalating from S-1 60 mg/body (level 1) to 80 mg/body/day (level 2), and then to 100 mg/body/day (level 3).

Twenty-one patients were valid for safety. Eighteen patients were enrolled in the dose-escalation phase. In all patients, S-1 was administered. The maximum tolerated dose was determined to be 100 mg/body/day and the dose-limiting toxicity was indicated by the onset of grade 3 chemoradiation dermatitis. Therefore, the determined recommended dose of S-1 was 80 mg/body/day. Objective response according to Response Evaluation Criteria in Solid Tumors were observed in 20 of 21 patients who had measurable disease (95.2%).

Concurrent S-1 and radiotherapy was feasible and well tolerated, and was suggested to produce a worthwhile response in T2N0 glottic carcinoma. These results warrant further investigation, and a phase II has already been started.