Perioperative chemotherapy for locally advanced colorectal cancer.

Interventions: 1) All RAS wild-type: 6 courses of cetuximab+mFOLFOX6 or 4 courses of cetuximab+SOX is performed, followed by curative operarion. 2) All RAS mutant-type: 6 courses of FOLFOXIRI or SOXIRI is performed, followed by curative operation. Primary outcome(s): Response rate (judged by enhanced CT and MRI on 12 weeks after initiation of chemotherapy), Induction rate of curative operation Study Design: single arm study, open(masking not used), no treatment control/standard of care control, single assignment, treatment purpose