4. Colorectal liver metastases will be determined to be unresectable by a surgeon with expertise in hepatic surgery (equal to or greater than 10 resections performed in a year). A patient is defined as unresectable when distribution and extent of disease preclude margin negative resection (tumor contact with or involvement of all three major hepatic veins or portal confluence or a combination of involvement of main branches of portal veins and hepatic veins), but two adjacent hepatic segments with adequate vascular inflow and outflow are relatively spared (contain 4 or fewer lesions).