Association of surgical margin on prognosis after hepatectomy for colorectal cancer liver metastases with RAS mutations

Background

Although outcomes of treatment for colorectal cancer liver metastases (CRLM) have improved with multidisciplinary treatment, recurrence rates after resection of liver metastases are still high. Although surgical margin (SM) is considered irrelevant in the case of R0 resection, its effectiveness is still unclear. In this study, we investigated the prognostic association of SM in CRLM according to RAS status.

Methods

Of 220 patients who had undergone initial hepatic resection for CRLM at our hospital between January 2000 and February 2020, finally, 164 remained in the study cohort. SMs (mms) were measured by macroscopic and microscopic examinations. Associations between SM, presence or absence of RAS mutations, and prognosis were analyzed using multivariate analysis with the Cox proportional hazards model.

Results

Of the 164 patients, 68 (41 %) had RAS mutations. The RAS mutation group had significantly poorer disease-free survival (DFS) (P < 0.001) and over-all survival (OS) (P < 0.001). In the RAS wild group, SM status was not significantly associated with OS or DFS, whereas in the RAS mutation group, SM< 2 mm was significantly associated with worse DFS (P = 0.014). Multivariate analysis showed that SM< 2 mm was an independent predictor of poor DFS in the RAS mutation group (HR 21.3, 95 % CI: 2.25–201.3, P = 0.008).

Conclusions

RAS mutation status is an independent predictor of poor prognosis after hepatectomy for CRLM. Especially in patients with RAS mutations, SM < 2 mm is associated with significantly worse post-hepatectomy DFS, suggesting achieving a wide SM (≥2 mm) is indicated in patients with RAS mutations

Synopsis

RAS mutation is an independent predictor of poor prognosis after hepatectomy for CRLM. Especially in patients with RAS mutations, SM < 2 mm is associated with significantly worse post-hepatectomy DFS, suggesting achieving a wide SM (≥2 mm) is indicated.