Simultaneous versus Staged Resection for Synchronous Colorectal Liver Metastases: The Win Ratio Approach

Introduction: The optimal surgical approach for synchronous colorectal liver metastases(sCRLM) remains controversial. We sought to assess the relative benefit of simultaneous versus staged resection of sCRLM through the “win ratio”(WR), a novel statistical approach. Methods: Patients undergoing hepatectomy for sCRLM between 2008-2018 were identified from an international multi-institutional database. Outcomes of patients undergoing simultaneous versus staged resection were compared using the WR approach; paired matching based on age, lymph node(LN) status, number and size of tumors, extent of liver resection and margin status was performed. A “win” was determined through a hierarchical composite outcome of no 90-day mortality, no severe complications(Clavien-Dindo > III), and long-term overall survival(OS). Results: Among 1,116 patients, 642(57.5%) presented with sCRLM; 290(45.2%) underwent simultaneous resection of the colorectal primary and sCRLM, while 352(54.8%) underwent staged resection. Median number of sCLRM was 2(IQR:1-4) and median size of largest metastatic lesion was 2.8 cm(IQR:1.7-4.5cm). Unadjusted 90-day mortality(simultaneous,3.5%vs. staged,1.7%), severe morbidity(simultaneous,19.3%vs. staged,8.2%), and 5-year OS(simultaneous,44.7%vs. staged,41.7%) were comparable. 102,080 total pairs(simultaneous-staged resection cohorts) were generated, resulting in 5,289 pairs after matching on relevant clinical characteristics. Staged resection yielded a WR of 1.59(95%CI 1.47-1.71) over the simultaneous approach. The highest WR for staged over simultaneous resection occurred among patients requiring a colectomy and a major hepatectomy(WR=1.93,95%CI 1.77-2.10). The WR for a staged approach was more modest among patients requiring a colectomy with a minor liver resection(WR=1.55,95%CI 1.44-1.70). Conclusions: Staged resection was superior to simultaneous resection for sCRLM based on a hierarchical composite endpoint that included 90-day mortality, severe complications, and 5-year survival.