A Phase I study of concurrent radiotherapy and capecitabine as adjuvant treatment for operable rectal cancer

Purpose: To determine the maximum tolerated dose and the dose-limiting toxicity of capecitabine with standard radiotherapy (RT) as adjuvant treatment in patients with rectal cancer. Methods and Materials: Patients with Stage II/III rectal cancer after surgery were eligible. Total RT dose was delivered as DT 50 Gy in fractions of 2.0 Gy/day for 5 weeks to the pelvic area. Capecitabine was administered concurrently with RT in escalating doses, twice daily with a 12-h interval, for two cycles of 14 days separated by a 7-day rest. Dose-limiting toxicity included Grade 3 or Grade 4 hematologic and nonhematologic toxicity. Results: Twenty-four patients were enrolled at the following dose levels: 1,000 (3 patients), 1,200 (3 patients), 1,400 (3 patients), 1,500 (3 patients), 1,600 (6 patients), and 1,700 mg/m2/day (6 patients). Dose-limiting toxicity was observed in 1 patient at 1,600 mg/m2/day (Grade 3 diarrhea) and in 2 patients at 1,700 mg/m2/day (1 patient had Grade 3 and 1 Grade 4 diarrhea). Conclusion: The maximum tolerated dose (MTD) of capecitabine given concurrently with RT was 1,600 mg/m2, daily from the 1st to the 14th day, with a 7-day rest, for two cycles