KRAS Mutation Status Dictates Optimal Surgical Margin Width in Patients Undergoing Resection of Colorectal Liver Metastases.

Abstract

The optimal tumor-free margin width remains controversial and may be inappropriate to investigate without considering differences in the underlying tumor biology. R1 resection was defined as margin clearance less than 1mm. R0 resection was further divided into 3 groups: 1-4, 5-9, and ≥10mm. The impact of margin width on overall survival (OS) relative to KRAS status [wild type (wtKRAS) vs. mutated (mutKRAS)] was assessed. A total of 411 patients met inclusion criteria. Median patient age was 58years (interquartile range, 49.7-66.7); most patients were male (n=250; 60.8%). With a median follow-up of 28.3months, median and 5-year OS were 69.8months and 55.1%. Among patients with wtKRAS tumors, although margin clearance of 1-4mm or more was associated with improved OS compared to R1 (all P<0.05), no difference in OS was observed when comparing margin clearance of 1-4mm to the 5-9mm and the ≥10mm groups (all P>0.05). In contrast, among patients with mutKRAS tumors, all three groups of margin clearance (1-4, 5-9, and ≥10mm) fared no better in terms of 5-year survival compared to R1 resection (all P>0.05). While a 1-4mm margin clearance in patients with wtKRAS tumors was associated with improved survival, wider resection width did not confer an additional survival benefit. In contrast, margin status-including a 1cm margin-did not improve survival among patients with mutKRAS tumors.