Adjuvant chemotherapy for isolated resectable colorectal lung metastasis: A retrospective study using inverse probability treatment weighting propensity analysis

BACKGROUND The benefit of adjuvant chemotherapy (ACT) for patients with no evidence of disease after pulmonary metastasis resection (PM) from colorectal cancer (CRC) remains controversial. AIM To assess the efficacy of ACT in patients after PM resection for CRC. METHODS This study included 96 patients who underwent pulmonary metastasectomy for CRC at a single institution between April 2008 and July 2023. The primary endpoint was overall survival (OS); secondary endpoints included cancer-specific survival (CSS) and disease-free survival (DFS). An inverse probability of treatment-weighting (IPTW) analysis was conducted to address indication bias. Survival outcomes compared using Kaplan-Meier curves, log-rank test, Cox regression and confirmed by propensity score-matching (PSM). RESULTS With a median follow-up of 27.5 months (range, 18.3-50.4 months), the 5-year OS, CSS and DFS were 72.0%, 74.4% and 51.3%, respectively. ACT had no significant effect on OS after PM resection from CRC [original cohort: P = 0.08; IPTW: P = 0.15]. No differences were observed for CSS (P = 0.12) and DFS (P = 0.68) between the ACT and non-ACT groups. Multivariate analysis showed no association of ACT with better survival, while sublobar resection (HR = 0.45; 95%CI: 0.20-1.00, P = 0.049) and longer disease-free interval (HR = 0.45; 95%CI: 0.20-0.98, P = 0.044) were associated with improved survival. CONCLUSION ACT does not improve survival after PM resection for CRC. Further well-designed randomized controlled trials are needed to determine the optimal ACT regimen and duration.