Stereotactic Body Radiation Therapy (SBRT) in Liver Metastasis (COLD 3)

Inclusion Criteria: * Eligible patients must have liver metastases from colorectal cancer 1) with histologic confirmation of metastases, 2) histologic confirmation of primary cancer and multiple new enhancing lesions in the liver consistent with metastases, or 3) histologic confirmation of primary cancer and a growing enhancing lesion in the liver Phase II SBRT Mets 13 consistent with a metastases * Either 1) the tumour must be unresectable, based on the opinion of an experienced surgeon specializing in hepatic resection, or 2) the patient must be medically inoperable, or 3) extra-hepatic metastases must be present (making hepatic surgery an inappropriate treatment option). * Karnofsky performance status (KPS) \> 60 (Appendix II) * Age: 18 years or older. Both male \& female patients of all races can be included in this study. Female patients within reproductive years may not be, nor become, pregnant during participation in this study * Patients must have recovered from the effects of previous therapy * Maximal tumor size of 15 cm * Adequate organ function as assessed as follows: * Hemoglobin \> 90 g/L * Absolute neutrophil count \> 1.0 bil/L * Platelets \> 60bil/L * Bilirubin \< 4.0 times upper range of normal * INR \< 1.5 or correctable with vitamin K (unless patients are on anticoagulation doses that have been stable for the past 2 months and they haven't had a bleed in the past 2 months) * AST or ALT \< 6.0 times upper limit of normal range * Child's A 5-6 liver score * Previous liver resection or ablative therapy is permitted * Life expectancy \> 3 months * The volume of uninvolved must be at least 700 cc * Up to five discrete liver tumors * Patients must have signed a study-specific informed consent form. If the patient's mental status precludes this, written informed consent may be given by the patient's legal representative. Exclusion Criteria: * Patients with active hepatitis or encephalopathy related to liver failure * Prior radiation therapy to the right upper abdomen, precluding reirradiation of the liver. That is, any previous radiation therapy in which a mean dose to the liver of 15 Gy in conventional fractionation was delivered, or previous doses to critical normal structures that would make re-irradiation unsafe. The PI should be called if there is any question of safety of re-irradiation. * Prior uncontrolled, life threatening malignancy within the six months. * Pregnancy is not permitted, and in women of child bearing age, a pregnancy test and acceptable methods of contraception are warranted. * Previous variceal bleed within the past 2 months