Posthepatectomy but not prehepatectomy chemotherapy was associated with a longer time to recurrence in patients with resectable colorectal liver metastases: Inverse probability of treatment weighting analysis

Background Patients with resectable colorectal liver metastases (CLM) are treated with surgery alone, surgery and posthepatectomy chemotherapy, or prehepatectomy chemotherapy and surgery. The optimal approach in terms of survival is unclear. We compared survival in the three treatment groups using inverse probability of treatment weighting (IPTW) analysis. Methods Data from patients undergoing initial CLM resection in 2005–2018 were obtained from a prospectively maintained database. Our group treated resectable CLM with surgery alone but gradually adopted post‐ and prehepatectomy chemotherapy for patients with CLM number ≥5 after 2015. IPTW analysis was employed to adjust the characteristics of the three groups. Results Of the 439 patients meeting the inclusion criteria, 175 underwent surgery alone, 135 underwent surgery and posthepatectomy chemotherapy, and 129 underwent prehepatectomy chemotherapy and surgery. After the IPTW adjustment, the demographic and clinicopathological characteristics were well balanced. The IPTW analysis revealed that the recurrence‐free survival was better in patients undergoing surgery and posthepatectomy chemotherapy than in patients undergoing surgery alone (median recurrence‐free survival, 1.3 years vs 0.7 years; P = .018). Overall survival was not significantly different between the three treatment approaches. Conclusion Posthepatectomy but not prehepatectomy chemotherapy prolongs the time to recurrence after curative‐intent resection of CLM.