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

Inclusion Criteria: * Participants must have biopsy-proven diagnosis of a colorectal cancer with 1-4 liver metastases. There is no upper size limit and participants must have at least 800 mL of uninvolved liver. Liver metastases may be diagnosed by imaging alone, no liver biopsy is required. Extrahepatic disease is allowed if 1) it has been stable for 3 months prior to study entry, 2) the dominant disease burden is intrahepatic and 3) the patient is referred for definitive radiation therapy to the disease in the liver. * Participants must have measurable disease, defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded) as ≥ 10 mm with spiral CT scan. See Section 13 for the evaluation of measurable disease. * Participants may have had prior chemotherapy, targeted biological therapy (i.e. sorafenib), surgery, transarterial chemoembolization (TACE), radiofrequency ablation, or cryosurgery for their disease as long as the prior therapy occurred more than 3 weeks before the first radiation treatment. Patients may not have had prior liver directed radiation, including radioembolization. * Participants must be 18 years of age or older. * Because no dosing or adverse event data are currently available on the use of high dose liver radiation in participants \<18 years of age, children are excluded from this study. * Expected survival must be greater than three months. * ECOG Performance Status 0 or 1.. * Participants m…