OBJECTIVEThis phase I study is to determine the maximal tolerated dose and the dose-limiting toxicity of capecitabine combined with standard radiotherapy (RT) as postoperative adjuvant treatment for rectal cancer patients.

METHODSStage II/III rectal cancer patients 18 - 75 years of age had undergone curative surgery with Karnofsky score > or = 70% were eligible to be included in this study. Total dose of RT DT 50 Gy was delivered to the pelvic area in fraction of 2.0 Gy per day for 5 weeks. Capecitabine was orally administered concurrently with radiotherapy for a total of 2 cycles in escalating doses: twice daily at 12 hour interval for consecutive 14 days as one cycle, separated by a seven day rest, then followed by another cycle. From March 2004 to May 2005, 24 patients were included and treated at the following dose levels: daily 1000 mg/m(2) (3 patients), 1200 mg/m(2) (3 patients), 1400 mg/m(2) (3 patients), 1500 mg/m(2) (3 patients), 1600 mg/m(2) (6 patients), and 1700 mg/m(2) (6 patients). Dose-limiting toxicities (DLT) including grade 3 or grade 4 hematologic and nonhematologic toxicity were observed.

RESULTSDose-limiting toxicity was observed in one patient treated at dose of 1600 mg/m(2) with grade 3 diarrhea, and in 2 patients at dose of 1700 mg/m(2) with one grade 3 and one grade 4 diarrhea.

CONCLUSIONDiarrhea is the most common dose-limiting toxicity. In our study, the maximal tolerated dose (MTD) of capecitabine given concurrently with radiotherapy was daily 1600 mg/m(2), from D1 to D14 separated by 7-day rest for 2 cycles. Capecitabine given concurrently with standard radiotherapy is safe and tolerable for operated stage II/III rectal cancer patients.