Laparoscopic Microwave Ablation vs Resection for Small Solitary Colorectal Liver Metastases: Multicenter Analysis of Long-Term Results

Background: Although traditionally reserved for unresectable lesions, recent studies have provided evidence that in selected patients, microwave ablation (MWA) may provide similar oncologic outcomes compared to liver resection (LR). This study aimed to compare oncologic outcomes of patients with solitary small (<3 cm) colorectal liver metastasis (CRLM) undergoing LR vs laparoscopic MWA. Study Design: This retrospective study included patients with a solitary CRLM <3cm treated with LR or MWA in three centers over 25-years. Two groups were compared using Wilcoxon, Chi-square, Kaplan-Meier survival, and Cox multivariate Hazards analyses. Continuous data are presented as median (interquartile range p25-75). Results: 221 patients underwent MWA, and 229 patients underwent LR. Among the patients who underwent either MWA (n=158) or LR (n=218) as the first line of local liver treatment, ablation patients were older [61(53-72) vs 59 (51-68) years, p=0.01), had a higher age-adjusted Charlson Comorbidity index [10 (9-11) vs 8 (7-9), p<.0001) and a higher percentage of tumors located in posterosuperior segments (63.3% vs 53.2%, p=0.05). The two groups were otherwise similar in terms of sex, body mass index, CEA level, tumor size, and perioperative chemotherapy exposure. After a median follow-up of 76 months, there was no difference in overall survival (5-year 51.5% vs. 56.7%, respectively, p=0.6404) or disease-free survival (5-year 30.5% vs. 36.2%, respectively, p=0.1042) between the groups. Hospital stay was longer [4 (3-6) days vs 1 (1-3) days, p<.0001] in the LR group. Conclusions: In this multi-institutional study, laparoscopic MWA and resection had comparable outcomes in terms of disease-free survival and overall survival for < 3 cm CRLM. Our findings support the noninferiority of ablation versus resection for surgical treatment of small solitary CRLM in appropriate patients.