Celecoxib, Fluorouracil, and Radiation Therapy in Treating Patients With Stage II or Stage III Rectal Cancer That Can Be Removed By Surgery

RATIONALE: Celecoxib may stop the growth of tumor cells by blocking blood flow to the tumor and by blocking some of the enzymes needed for cell growth. Drugs used in chemotherapy, such as fluorouracil, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Radiation therapy uses high-energy x-rays to kill tumor cells. Celecoxib may make tumor cells more sensitive to radiation therapy. Giving celecoxib together with fluorouracil and radiation therapy before surgery may make the tumor smaller and reduce the amount of normal tissue that needs to be removed.
PURPOSE: This phase II trial is studying how well giving celecoxib together with fluorouracil and radiation therapy works in treating patients with stage II or stage III rectal cancer that can be removed by surgery.