Outcomes after Surgical Microwave Ablation for the Treatment of Colorectal Liver Metastasis

Background: Colorectal cancer (CRC) is the third most common cause of cancer mortality worldwide. Of these, approximately 25% will have liver metastasis. We performed 394 microwave ablations (MWA) and analyzed outcomes for survival and ablation failure. Study Design: Retrospective review of patients who underwent a surgical microwave ablation at a single center high-volume institution from October 2006 through September 2022 using a prospectively maintained database. Primary outcome was overall survival. Results: A total of 394 operations were performed on 328 patients with 842 tumors undergoing MWA. Median tumor size was 1.5 cm (range 0.4-7.0 cm), with the median number of tumors ablated per operation being 1 (range 1-11). A laparoscopic approach was used 77.9% of the time. Concomitant procedures were performed 63% of the time, most commonly hepatectomy (22.3%), cholecystectomy (17.5%), and colectomy (6.6%). Clavien-Dindo Grade III or IV complications occurred in 12 patients (3.6%), and all of these patients had undergone concomitant procedures. Mortality within 30 days occurred in 4 patients (1.2%). The rate of incomplete ablation (IA) was 1.5% per tumor. Local recurrence (LR) occurred at a rate of 6.3% per tumor. African Americans were found to have a higher incidence of IA and LR. One year survival probability was 91% [95% CI: 87.9 -94.3], with a mean overall survival of 57.6 months [95% CI: 49.9-65.4 months] Conclusion: Surgical MWA offers a low-morbidity approach to treatment of colorectal liver metastasis (CRLM), with low rates of failure. This large series reviews the outcomes of MWA as definitive treatment for CRLM.