Liver resection after chemotherapy for liver only metastasis from colorectal cancer

Interventions: Chemotherapy with modified FOLFOX6 plus BV(bevacizumab). Treatment repeats every 14 days for up to 6 courses (5 courses for BV) in the absence of disease progression or unacceptable toxicity. Liver resection (if possible, 4 to 8 weeks after modified FOLFOX6 plus BV) Primary outcome(s): Curative resection rate (R0 resection rate) [in all subjects] Study Design: Single arm Non-randomized