Xeloda (Capecitabine) and External Beam Radiation

The Study Treatment: Radiation therapy and capecitabine are both designed to interfere with the growth of cancer cells. Study Therapy: If you are found to be eligible to take part in this study, you will receive radiation therapy once or twice a day, 5 days a week, for about 5 -7 weeks. The schedule and number of weeks will be the doctor's decision based on the type of breast cancer. The radiation treatments will take about 15-30 minutes each time. You will take the Capecitabine pills by mouth every day during the 5-7 weeks that you receive radiation therapy. The pills should be taken 2 times a day, about 12 hours apart, 30 minutes after eating food. On the radiation therapy days, you will take capecitabine about 2 hours before the radiation therapy. You will be given a pill diary in which you should record what time you take each dose of capecitabine. Study Visits: Once a week while you are receiving study treatment, you will have a physical exam. Length of Study: You may remain on study treatment for up to 7 weeks. You will be taken off study treatment early if the disease gets worse or intolerable side effects occur. Based on the status of the cancer, if you become eligible to have surgery after radiation, you will be referred to a surgeon to discuss that option. Follow-Up Visits: At Month 3 after finishing radiation therapy (or surgery, if applicable), you will have a positron emission tomography / computed tomography (PET/CT) scan or ultrasound to check the status of the disease. At Months 9, 17, and 29 after finishing radiation therapy or surgery, you may have a PET/CT scan, ultrasound, and/or routine blood tests if your doctor thinks it is needed. The amount of blood drawn, if any, will be the doctor's decision based on routine care. This is an investigational study. Capecitabine is commercially available and FDA approved to treat breast cancer that has spread. Radiation therapy is also commonly used to treat breast cancer. The combination of capecitabine and radiation therapy is commonly used to treat rectal cancer. At this time, it is considered investigational to give the combination of capecitabine and radiation therapy to patients with breast cancer. Up to 60 patients will take part in this study. All will be enrolled at M. D. Anderson.