Retrospective analysis of randomized phase II trial (WJOG6210G) of FOLFIRI with either panitumumab or bevacizumab as second-line treatment in patients with KRAS wild metastatic colorectal cancer refractory to oxaliplatin and bevacizumab to evaluate the association of survival time and treatment efficacy (early tumor shrinkage, depth of response and best overall response) at each arm

Primary outcome(s): To evaluate the association of survival time (progression-free survival, overall survival) and treatment efficacy (early tumor shrinkage, depth of response and best overall response) at each arm (FOLFIRI+BV, FOLFIRI+Pmab) for metastatic colorectal cancer as second-line chemotherapy.