Celecoxib in Preventing Hand/Foot Syndrome Caused By Capecitabine With Metastatic Breast or Colorectal Cancer

RATIONALE: Radiation therapy uses high energy x-rays to kill tumor cells. Drugs used in chemotherapy, such as capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving radiation therapy together with capecitabine may kill more tumor cells. Celecoxib may prevent or lessen hand-foot syndrome caused by capecitabine. PURPOSE: This randomized phase III trial is studying how well celecoxib works in preventing hand/foot syndrome caused by capecitabine in patients with metastatic breast or colorectal cancer.