RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Monoclonal antibodies, such as bevacizumab, can block tumor growth in different ways. Some block the ability of tumor cells to grow and spread by blocking blood flow. Others find tumor cells and help kill them or carry tumor-killing substances to them. Radiofrequency ablation uses high-frequency electric current to kill tumor cells. It is not yet known if chemotherapy is more effective with or without radiofrequency ablation in treating liver metastases.