Influence of KRAS mutation on recurrence patterns in patients undergoing hepatic resection of colorectal metastases.

Abstract

398 Background: There have been conflicting results about whether KRAS mutation influences outcome in patients (pts) with colorectal cancer. In pts who underwent liver resection, Karagkounis reported a worse recurrence and survival in KRAS mutated (MUT) patients (ASCO 2012, abs 3616). Methods: In 105 pts who underwent liver resection and received adjuvant (adj) hepatic arterial infusion and systemic chemotherapy and in whom KRAS data was available, we evaluated recurrence patterns and survival. Correlation between KRAS and clinical factors such as prior chemotherapy, post operative CEA, clinical risk score, and stage at diagnosis was evaluated using Fisher’s exact test and the Wilcoxon rank sum test. Kaplan-Meier methods were used to estimate median overall recurrence free survival (RFS) and overall survival (OS) at 4 years. Log-rank test was used to determine whether survival functions differed by KRAS mutation status. Cumulative incidence function was used to estimate the probability of time from adj therapy to bone, brain, lung and liver metastases separately. Results: Of 105 patients, 76 were KRAS wildtype (WT), and 29 were KRAS MUT (26-G12 and 3-G13). The median RFS was 26 months for KRAS WT pts and 15 months for KRAS MUT pts (p=0.08). OS at 4 years was 88% [95% CI: 78%-94%] for KRAS WT and 78% [95% CI: 57%-90%] for KRAS MUT pts (p= 0.15). Cumulative incidence of developing bone, brain, lung, and liver metastases by 2 years is presented in the Table. The cumulative incidence of bone and brain metastases at 2 years was 0% and 0% in KRAS WT pts versus 16.4% [95% CI: 1.1%-31.7%] and 4.7% [95% CI: 0%-14.1%] in KRAS MUT pts (Table). There was no association between clinical factors and KRAS status. Conclusions: KRAS MUT pts appeared to have worse OS and RFS, although we were unable to show a significant difference between KRAS WT and MUT for OS and RFS. In addition, cumulative incidence of bone and brain metastases at 2 years appeared to be higher for KRAS MUT pts as compared to WT pts. Results are based on small sample size and further investigation is needed. [Table: see text]