Reappraisal of Multidisciplinary Treatment Approach for Resectable Colorectal Liver Metastases: Inverse Probability of Treatment Weighted Analysis

Abstract

Introduction: Three multidisciplinary treatment approaches are used for patients with resectable colorectal liver metastases (CLM): surgery alone, surgery and posthepatectomy chemotherapy, and prehepatectomy chemotherapy and surgery. However, it remains unclear which approaches improve survival after CLM resection. We aimed to assess survival after CLM resection by three groups using inverse probability of treatment weighted (IPTW) analysis. Methods: From a prospectively maintained database, patients undergoing initial CLM resection during 2005–2018 were included. Prehepatectomy chemotherapy for resectable CLM was not generally performed before 2015, but after 2015, performed for patients with CLM number ≥ 5. IPTW analysis was used to adjust characteristics of three groups. Results: Of the 439 patients meeting the inclusion criteria, 175 patients underwent surgery alone (SUR group), 135 underwent surgery and posthepatectomy chemotherapy (SUR+Post-chemo), and 129 underwent prehepatectomy chemotherapy and (Pre-chemo+SUR). Age, sex, synchronous vs. metachronous, and CLM number were significantly different between the groups. After IPTW adjustment, demographics and clinicopathologic characteristics were well balanced (e.g., median CLM number. 2 vs. 2 vs. 2, p=0.997). The IPTW analysis showed that overall survival (OS) and recurrence-free survival (RFS) did not differ significantly (Figure 1): 5-year OS, SUR vs. SUR+Post-chemo vs. Pre-chemo-SUR, 61.5% (reference), 65.3% (hazard ratio [HR], 0.73; p=0.140) and 59.2% (HR, 0.91; p=0.652), 5-year RFS, 30.5% (reference), 29.0% (HR, 0.82; p=0.191) and 21.7% (HR, 1.06; p=0.706). Conclusion: Survival after three treatment approaches for resectable CLM was not significantly different using IPTW analysis. Combination of chemotherapy with surgery may not be associated with improved OS for resectable CLM.