Thermal ablation versus hepatectomy for solitary colorectal liver metastases up to 5 cm: a multicenter target trial emulation on safety, efficacy, and cost-effectiveness

BACKGROUND: No randomized trials or large-scale observational studies directly compared thermal ablation (TA) and hepatectomy (HT) for solitary colorectal liver metastases (SCLM) ≤ 5 cm with long-term follow-up. METHODS: In this multicenter target trial emulation (2009-2024), 1,334 patients with SCLM ≤ 5 cm from 21 Chinese hospitals were enrolled. Propensity score matching (1:1) balanced baseline characteristics, yielding 437 matched pairs. Primary and secondary endpoints were progression-free survival (PFS) and overall survival (OS), respectively. Complications, hospital stay, and costs were analyzed. Sensitivity analyses were performed to evaluate the robustness of the results. RESULTS: After matching, median PFS was 1.81 years (95% CI 1.60-2.04) for TA vs 1.95 years (1.67-2.34) for HT (HR 0.94, 95% CI 0.82-1.09; P = 0.41). Median OS was 7.22 years (6.43-9.05) for TA vs 8.09 years (6.68-10.58) for HT (HR 0.89, 0.71-1.11; P = 0.30). The Five-year PFS and OS rates were comparable between groups. The PFS rates were 30.05% (95% CI: 25.32%-35.67%) for TA and 32.16% (95% CI: 27.49%-37.63%) for HT, while OS rates were 62.36% (95% CI: 56.24%-69.14%) for TA and 67.79% (95% CI: 62.38%-73.66%) for HT. TA reduced Clavien-Dindo III-IV complications (2.1% vs 5.0%; P = 0.017), hospital stay (median 3 vs 10 days; P < 0.001), and costs (median $4,820 vs $10,239; P < 0.001). Across all predefined subgroups (e.g., tumor size, CRS), treatment with TA resulted in PFS and OS comparable to those achieved with HT. CONCLUSIONS: For SCLM ≤ 5 cm, TA provides comparable oncologic outcomes to HT, alongside superior safety and cost-effectiveness. This supports its role as a first-line therapeutic alternative for selected patients or when surgery is contraindicated.