Preoperative Chemoradiotherapy with Capecitabine and Oxaliplatin in Locally Advanced Rectal Cancer. A Phase I–II Multicenter Study of the Dutch Colorectal Cancer Group

Abstract

Background We studied the maximum tolerated dose (MTD) and efficacy of oxaliplatin added to capecitabine and radiotherapy (Capox-RT) as neoadjuvant therapy for rectal cancer. Methods T3-4 rectal cancer patients received escalating doses of oxaliplatin (day 1 and 29) with a fixed dose of capecitabine of 1000 mg/m² twice daily (days 1–14, 25–38) added to RT with 50.4 Gy and surgery after 6–8 weeks. The MTD, determined during phase I, was used in the subsequent phase II, in which R0 resection rate (a negative circumferential resection margin) was the primary end point. Results Twenty-one patients were evaluable. In the phase I part, oxaliplatin at 85 mg/m² was established as MTD. In phase II, the main toxicity was grade III diarrhea (18%). All patients underwent surgery, and 20 patients had a resectable tumor. An R0 was achieved in 17/21 patients, downstaging to T0-2 in 7/21 and a pCR in 2/21. Conclusion Combination of Capox-RT has an acceptable acute toxicity profile and a high R0 resection rate of 81% in locally advanced rectal cancer. However the pCR rate was low.