Capecitabine + Irinotecan Followed by Combined Modality Capecitabine and Radiation in Locally Advanced Rectal Cancer

Preoperative induction chemotherapy has been successfully used in a variety of malignancies and provides several advantages over postoperative therapy. Combination of 5-FU/Leucovorin/CPT-11 has demonstrated significantly better response rate than 5-FU/Leucovorin alone. Replacing 5-FU with oral capecitabine in combination with CPT-11 has emerged as a potentially more effective, safe and convenient treatment option for metastatic colorectal cancer. Capecitabine is also well tolerated in concurrent treatment with radiation. Recent data has shown that preoperative radiation appears to be significantly more effective in increasing resectability rates. This trial will investigate the activity of capecitabine and CPT-11 combination in the preoperative setting followed by chemoradiation with capecitabine in locally advanced rectal cancer to improve response and decrease local recurrence. We will also study whether TS, TP, DPD and carboxyesterase expressions correlate with the objective response rate with this chemotherapy and chemoradiation regimen.