Oxaliplatin-based chemotherapy might provide longer progression-free survival in KRAS mutant metastatic colorectal cancer

The identification of better regimens in currently available chemotherapeutic agents is crucial for treating patients with KRAS mutant metastatic colorectal cancer (mCRC). Records of mCRC patients who received first-line oxaliplatin- based or irinotecan-based regimens were reviewed retrospectively. Clinicopathologic features and treatment outcome of patients with first-line progression-free survival (PFS) and overall survival (OS) in association with KRAS mutation status were analyzed using the Cox proportional hazard model. Between 2007 and 2010, a total of 118 mCRC patients were enrolled. Among them, 67 were males and 51 were females. In patients who received first-line oxaliplatin-based regimens, the PFS was significantly longer in KRAS mutant patients (N = 32) than that in KRAS wild-type patients (N = 51). The median PFS was 8.5 months in KRAS mutant versus 5.8 months in KRAS wild-type patients (P =.008). In contrast, in patients who received first-line irinotecan-based regimens, the PFS was shorter in KRAS mutant patients (N = 15) than that in KRAS wild-type patients (N = 20). Median PFS was 3.9 months in KRAS mutant versus 6.0 months in KRAS wild-type patients (P =.23). Median OS between KRAS mutant and wild-type patients was not significantly different in both oxaliplatin-based and irinotecan-based regimens. In multivariate analyses, KRAS mutation remains an independent predictive factor for longer PFS in first-line oxaliplatin-based regimens. In conclusion, oxaliplatin-based chemotherapy in KRAS mutant mCRC might result in longer PFS than in KRAS wild-type mCRC.