Chemotherapy Plus Radiation Therapy in Treating Patients With Unresectable, Residual, or Recurrent Colorectal Cancer

RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Radiation therapy uses x-rays to damage tumor cells. Drugs such as capecitabine may make the tumor cells more sensitive to radiation therapy. PURPOSE: Phase I trial to study the effectiveness of capecitabine in combination with radiation therapy in treating patients who have unresectable, residual, or recurrent colorectal cancer located in the pelvis.