Impact of anatomical liver resection on patient survival in KRAS-wild-type colorectal liver metastasis: A multicenter retrospective study.

Background: Liver resection is a standard therapy for colorectal liver metastasis. However, the impact of anatomical resection and nonanatomical resection on the survival in patients with Kirsten rat sarcoma-wild-type and Kirsten rat sarcoma-mutated colorectal liver metastasis remain unclear. We investigated whether anatomical resection versus nonanatomical resection improves survival in colorectal liver metastasis stratified by Kirsten rat sarcoma mutational status.

Methods: Among 639 consecutive patients with colorectal liver metastasis who underwent primary liver resection between January 2008 and December 2017, 349 patients were excluded due to their unknown Kirsten rat sarcoma mutational status, or due to receiving anatomical resection with concomitant non-anatomical resection, radiofrequency, or R2 resection. Accordingly, 290 patients with colorectal liver metastasis were retrospectively assessed. The relationships between resection types and survival were investigated in Kirsten rat sarcoma-wild-type and -mutated groups.

Results: Anatomical resection was performed in 77/186 (41%) and 44/104 (42%) patients with Kirsten rat sarcoma-wild-type and Kirsten rat sarcoma-mutated genetic statuses, respectively. For both, the clinical-pathologic factors were comparable, except a larger maximum tumor size and surgical margin were observed in anatomical resection cases. Anatomical resection patients had significantly longer recurrence-free survival and overall survival than nonanatomical resection cases in the Kirsten rat sarcoma-wild-type group (recurrence-free survival, P < .001; overall survival, P = .005). No significant recurrence-free survival or overall survival differences were observed between Kirsten rat sarcoma-mutated anatomical resection and non-anatomical resection (recurrence-free survival, P = .132; overall survival, P = .563). Although, intrahepatic recurrence in Kirsten rat sarcoma-wild-type and -mutated colorectal liver metastasis was comparable (P = .973), extrahepatic recurrence was increased in Kirsten rat sarcoma-mutated versus -wild-type colorectal liver metastasis (P < .001).

Conclusion: In contrast to Kirsten rat sarcoma-mutated colorectal liver metastasis with higher extrahepatic recurrence after liver resection, local liver control via anatomical resection improved the postoperative survival in patients with Kirsten rat sarcoma-wild-type colorectal liver metastasis.