Study of TAS-102 Plus Radiation Therapy for the Treatment of the Liver in Patients With Hepatic Metastases From Colorectal Cancer

This is a Phase I/II clinical trial. Patients are being asked to participate in the Phase I portion of the study. A Phase I clinical trial tests the safety of an investigational intervention and also tries to define the appropriate dose of the investigational drug to use for further studies. "Investigational" means that the intervention is being studied. The FDA (the U.S. Food and Drug Administration) has approved Trifluridine as a treatment option for this disease. The FDA has not approved Trifluridine in combination with radiation therapy as a treatment option for this disease. In this research study, the investigators are determining the safest and most effective dose of Trifluridine in combination with radiation therapy in participants with hepatic metastases from colorectal cancer. Trifluridine stops DNA replication which may prevent the cancer cells from growing. Radiation may help to kill the cancer cells while protecting normal tissue cells. Studies have shown Trifluridine may make radiation more effective.