Background: The KRAS mutation status is reportedly correlated with poor survival outcome in patients with colorectal liver metastases (CLM); however, its true prognostic impact and the reason for the poor prognosis remain unclear.
Methods: Data on 163 patients with a known KRAS mutation status who underwent curative resection for CLM were retrospectively reviewed. The long-term survival and site-specific incidence of recurrence were then compared between patients with a KRAS mutation (mtKRAS) and those without a mutation (wtKRAS).
Results: The mtKRAS group had a poorer 3-year disease-specific survival (DSS) rate (59.8 vs. 83.6 %, p = 0.016), 3-year recurrence-free survival (RFS) rate (0 vs. 20.2 %, p = 0.069), and median time to surgical failure (TSF) [18.8 vs. 39.7 months, p = 0.001] than the wtKRAS group. The cumulative incidences of liver recurrence and lung recurrence at 3 years were also higher in the mtKRAS group (76.2 vs. 54.7 %, p = 0.060; and 71.9 vs. 37.3 %, p < 0.001, respectively). A multivariate analysis confirmed that an mtKRAS status had a significant effect on the DSS rate (hazard ratio [HR] 2.9, p = 0.006), RFS (HR 2.0, p = 0.004), TSF (HR 2.4, p < 0.001), liver recurrence (HR 1.7, p < 0.001), and lung recurrence (HR 2.6, p < 0.001). Lung-related unresectable recurrences were more frequent (41 vs. 18 %, p = 0.048) and were associated with an earlier TSF (9.6 vs. 14.0 months, p = 0.14) in the mtKRAS group, regardless of the location of the primary lesions.
Conclusions: mtKRAS is associated with poor survival outcome after CLM resection because of a relatively high incidence of lung recurrence and a relatively short TSF.