Neoadjuvant Chemoradiotherapy and Adjuvant Chemotherapy in Treating Patients Who Are Undergoing Surgical Resection for Locally Advanced Rectal Cancer

RATIONALE: Drugs used in chemotherapy work in different ways to stop tumor cells from dividing so they stop growing or die. Radiation therapy uses high-energy x-rays to damage tumor cells. Chemoradiotherapy (combining chemotherapy with radiation therapy) before surgery may shrink the tumor so that it can be removed. Giving chemotherapy after surgery may kill any remaining tumor cells.
PURPOSE: This randomized phase II trial is studying two different regimens of neoadjuvant chemoradiotherapy and adjuvant chemotherapy and comparing how well they work in treating patients who are undergoing surgical resection for locally advanced rectal cancer.