Phase II trial of mFOLFOX6/XELOX plus bevacizumab with oxaliplatin in a stop and go fashion in advanced metastatic colorectal cancer

Interventions: 6 cycles of bi-weekly mFOLFOX6 plus bevacizumab regimen is followed by 6 cycles of bi-weekly sLV5FU2 plus bevacizumab regimen. Agter the 12 cycle treatment, 6 cycles of bi-weekly mFOLFOX6 plus bevacizumab regimen is re-administred. Or 4 cycles of Tri-weekly XELOX plus bevacizumab regimen is followed by 4 cycles of Trii-weekly Capacitabine plus bevacizumab regimen. After the 8 cycle treatment, 4 cycles of Tri-weekly XELOX plus bevacizumab regimen is re-administred. Primary outcome(s): median prpgression free survival (PFS) Study Design: Single arm Non-randomized