Radiation Therapy Before Surgery Compared With Chemotherapy Plus Radiation After Surgery in Treating Patients With Rectal Cancer That Can Be Surgically Removed

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. It is not yet known whether giving radiation therapy before surgery is more effective than giving chemotherapy plus radiation therapy after surgery in treating patients with rectal cancer.
PURPOSE: This randomized phase III trial is studying radiation therapy given before surgery to see how well it works compared to chemotherapy and radiation therapy given after surgery in treating patients with rectal cancer that can be surgically removed.