Liver-First Resection in Patients With Synchronous Colorectal Liver Metastases Is Associated with Inferior Recurrence-Free Survival: Reconsidering the Importance of the Primary Cancer.

BACKGROUND Synchronous colorectal liver metastases may be managed with primary-first, simultaneous, or liver-first resection. Relative oncologic outcomes based upon treatment sequencing are understudied. OBJECTIVE This study aimed to assess oncologic survival outcomes in patients with synchronous colorectal liver metastases managed with each of the three treatment strategies, with respect to early or delayed removal of the primary tumor. DESIGN Retrospective analysis of prospectively maintained database, with 1:1 propensity-matching of relevant clinicopathologic variables comparing liver-first to primary-first/simultaneous approaches. SETTINGS Single-institution, tertiary cancer center. PATIENTS Patients undergoing curative-intent hepatectomy for synchronous colorectal liver metastases from 2003-2019. MAIN OUTCOME MEASURES Overall and recurrence-free survival. RESULTS Of 151 patients, 23% (n = 35) had liver-first and 77% (n = 116; primary-first = 93 and simultaneous = 23) had primary-first/simultaneous approaches. Median follow-up was 45 months. Recurrence-free survival was worse for liver-first versus primary-first/simultaneous groups (median 12 versus 16 months, p = 0.02), driven by three-year extrahepatic recurrence-free survival of 19%, 58%, and 50% for liver-first, primary-first, and simultaneous groups, respectively. Three-year overall survival was not significantly different at 86%, 79%, and 86%, respectively. Oncologic outcomes did not significantly differ between primary-first and simultaneous groups (all p > 0.4). Matching yielded 34 clinicopathologically similar patients per group (liver-first = 34, primary-first = 28/simultaneous = 6). The liver-first approach was associated with shorter recurrence-free survival (median 12 versus 23 months, p = 0.004), driven by extrahepatic recurrence-free survival (3-year: 20% versus 55%, p = 0.04). Overall survival was not significantly different at 3-years (79% versus 80%, p = 0.95) or 5-years (59% versus 59%, p > 0.99). LIMITATIONS This study has a retrospective design and limited sample size. CONCLUSIONS A liver-first approach is associated with worse recurrence free-survival compared to primary-first or simultaneous resection, driven by extrahepatic recurrence. Prospective study of whether oncologic risk is associated with leaving the primary in situ is needed. Multidisciplinary treatment sequencing and enhanced postoperative surveillance for patients receiving liver-first resection is recommended. See Video Abstract.