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

Background: 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.Methods: 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.Results: 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).Conclusion: A simultaneous approach was not associated with worse overall survival or morbidity compared to a liver-first approach.