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

ABSTRACT

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.