RESUMEN
We conducted a phase I study to determine a recommended dose (RD) of S-1 for chemo-radiotherapy consisting of S-1+ radiotherapy for T 2 N 0 larynx cancer. The method of administration used to assess the RD was irradiation with 2 Gy/day for 5 days a week until a total dose of 60 Gy, and concomitant administration 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/day (level 1) to 80 mg/body/day (level 2), and then to 100 mg/body/day (level 3). 18 patients were enrolled. 4 patients developed an adverse event of grade 3 radiation dermatitis which became a dose-limiting toxicity (DLT) at level 3. We then concluded that 100 mg/body/day was the maximum tolerated dose (MTD) of S-1 and decided that the RD of S-1 was 80 mg/body/day.