 RATIONALE: Drugs used in chemotherapy, such as capecitabine and oxaliplatin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving more than one drug combination chemotherapy may kill more tumor cells. Monoclonal antibodies, such as cetuximab and bevacizumab, can block tumor growth in different ways. Some block the ability of tumor cells to grow and spread. Others find tumor cells and help kill them or carry tumor-killing substances to them. Cetuximab and bevacizumab may also stop the growth of tumor cells by blocking blood flow to the tumor. Giving capecitabine together with cetuximab, oxaliplatin, and bevacizumab may kill more tumor cells. 