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.