Radiation Therapy and Chemotherapy Followed by Surgery and Combination Chemotherapy in Treating Patients With Rectal Cancer

RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Combining radiation therapy and chemotherapy may shrink the tumor so that it can be removed during surgery.
PURPOSE: Phase II trial to study the effectiveness of radiation therapy and chemotherapy followed by surgery and combination chemotherapy in treating patients who have stage II or stage III rectal cancer.