The effects of resection margin and KRAS status on outcomes after resection of colorectal liver metastases

Background: The aim of this study was to investigate the influence of resection margin status in patients with KRAS mutations (mt-KRAS) when compared to those with wild-type KRAS (wt-KRAS) on long-term outcomes in patients with resected CRLM. Methods: All patients who underwent resection of CRLM with curative intent between January 2011 and December 2016 and had a KRAS type recorded were included in the study. Overall survival (OS), as well as death-censored overall (RFS) and liver-specific (LS-RFS) recurrence-free survival between KRAS types and the margin status within KRAS subgroups were compared using Cox regression models. Results: Data were available for N = 500 patients (30.4% mt-KRAS). mt-KRAS status was independently associated with significantly shorter OS. Within the wt-KRAS subgroup, smaller margins were found to be associated with significantly shorter death-censored LS-RFS (p < 0.001), with HRs of 1.93 (p = 0.005) for 1–4 mm margins and 2.83 (p < 0.001) for <1 mm margins, relative to those with clear margins. No such association was observed in the mt-KRAS subgroup (p = 0.721). Conclusion: The resection margin status is of greater importance in patients with wt-KRAS. Such information could be useful in the operative planning, especially for those with multiple metastatic deposits, and also in the post-operative counselling and surveillance based on the margin and KRAS status.