Conditional Recurrence‐Free Survival After Hepatectomy for Colorectal Liver Metastases: Time‐Dependent Prognostic Relevance of Liver Metastasis Number

BACKGROUND AND OBJECTIVES: Recurrence risk after hepatectomy for colorectal liver metastases (CRLMs) changes during follow-up, but whether baseline tumor burden remains prognostically relevant with increasing recurrence-free time is unclear. We evaluated the time-dependent prognostic relevance of liver metastasis number. METHODS: We retrospectively analyzed 226 patients who underwent initial curative-intent hepatectomy for CRLMs between 2007 and 2022. Three-year conditional recurrence-free survival (RFS) was estimated at surgery and after 6, 12, and 24 months without recurrence. Landmark Cox models evaluated liver metastasis number (< 4 vs. ≥ 4), adjusting for RAS status, with supplementary expanded models. RESULTS: Three-year conditional RFS improved from 27.1% at surgery to 33.3%, 49.3%, and 76.6% after 6, 12, and 24 months without recurrence, respectively. However, subsequent RFS remained worse in patients with ≥ 4 liver metastases at the 6-month (adjusted hazard ratio [HR]: 1.83, 95% confidence interval [CI]: 1.14-2.94; p = 0.012) and 12-month (HR: 2.14, 95% CI: 1.08-4.27; p = 0.030) landmarks. In supplementary expanded models, the associations remained directionally similar but were attenuated. CONCLUSIONS: Recurrence risk improved with increasing recurrence-free time, but survivors remained heterogeneous according to baseline tumor burden. Liver metastasis number retained prognostic relevance at early postoperative landmarks.