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 with liver resection (LR). This study aimed to compare oncologic outcomes of patients with solitary small (less than 3 cm) colorectal cancer liver metastasis (CRLM) undergoing LR vs laparoscopic MWA.

[STUDY DESIGN] This retrospective study included patients with a solitary CRLM measuring less than 3 cm treated with LR or MWA in 3 centers over 25 years. Two groups were compared using the Wilcoxon test, chi-square test, Kaplan-Meier survival analysis, and Cox multivariate hazard analysis. Continuous data are presented as median (interquartile range p25 to 75).

[RESULTS] 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 to 72] vs 59 [51 to 68] years, p = 0.01), had a higher age-adjusted Charlson Comorbidity Index (10 [9 to 11] vs 8 [7 to 9], p < 0.0001) and a higher percentage of tumors located in posterosuperior segments (63.3% vs 53.2%, p = 0.05). The 2 groups were otherwise similar in terms of sex, BMI, 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 overall survival 51.5% vs 56.7%, respectively, p = 0.6404) or disease-free survival (5-year disease-free survival 30.5% vs 36.2%, respectively, p = 0.1042) between the groups. Hospital stay was longer (4 [3 to 6] days vs 1 [1 to 3] days, p < 0.0001) 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 less than 3 cm CRLM. Our findings support the noninferiority of ablation vs resection for the surgical treatment of small solitary CRLM in appropriate patients.