Oxaliplatin, Capecitabine, and Radiation Therapy in Treating Patients With Locally Advanced Cancer of the Rectum

RATIONALE: Drugs used in chemotherapy, such as oxaliplatin and capecitabine, 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. Oxaliplatin and capecitabine may make tumor cells more sensitive to radiation therapy and may kill more tumor cells. Giving chemotherapy with radiation therapy before surgery may shrink the tumor so that it can be removed.
PURPOSE: This phase I/II trial is studying the side effects and best dose of oxaliplatin and capecitabine when given together with radiation therapy and to see how well they work in treating patients who are undergoing surgery for locally advanced cancer of the rectum. NOTE: *The phase I portion of this trial closed 06/2005. The best dose of oxaliplatin and capecitabine has been determined.