Significance of KRAS mutation in patients receiving mFOLFOX6 with or without bevacizumab for metastatic colorectal cancer.

BACKGROUND/AIMS: KRAS mutation is an important prognostic factor for patients with metastatic colorectal cancer receiving anti-epidermal growth factor receptor therapy. However, the influence of KRAS mutation on the response to mFOLFOX6 ± bevacizumab remains unclear. METHODOLOGY: We retrospectively analyzed 49 patients who received modified FOLFOX6 (mFOLFOX6) ± bevacizumab as first-line therapy. Genetic analysis showed that 30 patients had wild-type (WT) KRAS and 19 patients hadKRAS mutations (MT). These two groups were compared with regard to the response rate (RR), progression-free survival (PFS), and overall survival (OS). RESULTS: The RR was not significantly different between the WT and MT groups, but PFS and OS were significantly better in the WT group than the MT group (PFS: 11.8 months vs. 8.7 months, p<0.01; OS: 37.8 months vs. 29.3 months, p<0.0385). A similar analysis of 27 patients who were treated with mFOLFOX6 + bevacizumab showed a better prognosis for WT patients. Multivariate analysis also revealed that KRAS mutation was an independent factor with a significant relation to PFS. CONCLUSIONS: These results suggest that KRAS mutation may be a useful prognostic marker for patients with metastatic colorectal cancer receiving mFOLFOX6 ± bevacizumab therapy, especially for patients treated with mFOLFOX6 + bevacizumab.