A Study of Bevacizumab, Infusional Fluorouracil, Leucovorin, Oxaliplatin, and Irinotecan (A-FOLFOXIRI) Compared With Bevacizumab, Infusional Fluorouracil, Leucovorin, and Irinotecan/Oxaliplatin (A-FOLFIRI/FOLFOX) as First-line Treatment for Metastatic Right-sided Colon Cancer

RATIONALE: Recently, the importance of prognosis according to the location of the primary tumor in colorectal cancer has been raised. In the CALGB / SWOG 80405 study published in 2016, the addition of bevacizumab or cetuximab to the first line FOLFIRI / FOLFOX in KRAS (codon 12, 13) wild type metastatic colorectal cancer (mCRC) patients did not show a significant difference between overall survival (OS) and progression free survival (PFS) in both groups. Alan P. Venook et al. published a follow-up subgroup analysis on the effect of primary tumor location at 2016 ASCO. In the treatment group with cetuximab, the difference in treatment effect was significant according to the primary tumor location. The right colon cancer showed a poor prognosis for cetuximab treatment. (PFS: 7.8 vs 12.4 months, HR 1.56, p \<0.0001 / OS: 16.7 vs 36.0months, HR 1.87, P \<0.0001). Therefore, the investigators propose a phase II trial for the efficacy evaluation of bevacizumab-FOLFOXIRI and bevacizumab-FOLFIRI or FOLFOX treatment in patients with poor prognosis of unresectable right-sided colorectal cancer.