Local recurrence after colorectal liver metastasis (CRLM) resection severely affects survival; however, the required surgical margin width remains controversial. This study investigated the impact of KRAS status on surgical margin width and local recurrence rate (LRR) post-CRLM resection. Overall, 146 resected CRLMs with KRAS status (wild-type KRAS (wtKRAS): 98, KRAS mutant (mKRAS): 48) were included. The LRR for each group, R1 (margin positive) and R0 (margin negative), was analyzed by KRAS status. R0 was further stratified into Ra (margin ≥ 5 mm) and Rb (margin < 5 mm). Patients with local recurrence had significantly worse 5-year overall survival than those without local recurrence (p = 0.0036). The mKRAS LRR was significantly higher than wtKRAS LRR (p = 0.0145). R1 resection resulted in significantly higher LRRs than R0 resection for both wtKRAS and mKRAS (p = 0.0068 and p = 0.0204, respectively), and while no significant difference was observed in the Ra and Rb LRR with wtKRAS, the Rb LRR with mKRAS (33.3%) was significantly higher than Ra LRR (5.9%) (p = 0.0289). Thus, R0 resection is sufficient for CRLM with wtKRAS; however, CRLM with mKRAS requires resection with a margin of at least 5 mm to prevent local recurrence.
Keywords: KRAS; colorectal metastasis; liver resection; local recurrence; mutant; surgical margin; wild type.