Capecitabine and Oxaliplatin or Standard Follow-Up Care in Treating Patients Who Have Undergone Surgery for Locally Advanced Rectal Cancer

RATIONALE: Drugs used in chemotherapy, such as capecitabine and oxaliplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving combination chemotherapy after surgery may kill any tumor cells that remain after surgery. It is not yet known whether giving capecitabine together with oxaliplatin is more effective than standard follow-up care in treating rectal cancer that was removed by surgery.
PURPOSE: This randomized phase III trial is studying capecitabine and oxaliplatin to see how well they work compared with standard follow-up care in treating patients who have undergone surgery for locally advanced rectal cancer.