KRAS Mutation Predicted More Mirometastases and Closer Resection Margins in Patients with Colorectal Cancer Liver Metastases

The presence of micrometastases is a source of recurrence after surgical resection of colorectal liver metastases (CRLM). The KRAS mutation is common in colorectal cancer, however the correlation between KRAS status and micrometastases has not been thoroughly clarified.

We enrolled a cohort of 251 consecutive CRLM patients who received complete liver surgery with known KRAS mutation status, and collected clinicopathological information, including micrometastases, margin status, preoperative chemotherapy, and liver recurrence-free survival (LRFS) and overall survival (OS) rates.

KRAS-mutant (mutKRAS) patients had a higher incidence (60.3 vs. 40.8%; p = 0.002) and higher number of micrometastases [2.0 (range 0–38.0) vs. 0 (range 0–15.0); p < 0.001] than KRAS wild-type (wtKRAS) patients. The micrometastases in the mutKRAS group were more distant than those in the wtKRAS group [0.7 (range 0.1–9.0) vs. 0.6 (range 0.2–5.0) mm; p = 0.018). The mutKRAS group had more involved margin resections (21.5 vs. 9.2%; p = 0.07) and narrower margin widths [2.0 (range 0–40.0) vs. 4.3 (0–50.0) mm; p = 0.002] than the wtKRAS group. In addition, preoperative chemotherapy was associated with a lower rate of micrometastases in mutKRAS CRLM tumors (p < 0.05). mutKRAS status, positive margins, and micrometastases were all related to worse LRFS and OS (p < 0.05); however, micrometastases were not significantly correlated with OS in the multivariate analysis (p = 0.106).

mutKRAS patients had more micrometastases, increased R1 resections, and narrower margins. The presence of micrometastases may have led to the narrow margin width observed in these cases.