A comparison of the simultaneous, liver-first, and colorectal-first strategies for surgical treatment of synchronous colorectal liver metastases at two major liver-surgery institutions in Sweden

The optimal treatment strategy for patients with synchronous colorectal liver metastases (CRLM) is unclear. The aim of this study was to compare the outcome of the simultaneous, liver-first, and colorectal-first surgical approaches.All consecutive patients who had been resected with curative intent for CRLM were included. A Cox regression model was constructed, and an intention-to-treat analysis was performed between the liver-first and the simultaneous approaches, after propensity score matching.658 patients were included in the analysis. 92 patients had a simultaneous resection, 163 patients had liver-first, and 403 patients had a colorectal-first approach. Overall survival was 54.9 months (95% CI 39.2-70.4) in the liver-first group, 54.5 months (95% CI 46.8-62.3) in colorectal-first group, and 59.6 months (95% CI 42.2-77.0) in the simultaneous group (log-rank p =0.850). In the matched cohort there were no differences in Clavien-Dindo 3a (p = 0.992) or 3b and greater (p = 0.999). Median overall survival was for liver-first group 42.2 months (95% CI 26.3-58.2), and for the simultaneous group 56.2 months (95% CI 47.1-65.4) (stratified log-rank p = 0.455).A simultaneous approach was not associated with worse overall survival or morbidity compared to a liver-first approach.