Microwave ablation of colorectal liver metastases: Impact of a 10-mm safety margin on local recurrence in a tertiary care hospital

Microwave ablation (MWA) for colorectal liver metastasis (CLM) has been traditionally considered inferior to surgery due to the higher rate of local recurrence. The study investigated whether a safety margin of 10 mm can improve local control in patients undergoing surgical MWA. Surgical MWA was used to treat 53 lesions in 22 patients with CLM at our Institution from June 2012 to June 2017. The patients’ mean age was 64.5 years, and the median size of the lesion was 16.5 mm (9–34 mm). MWA was associated with liver resection in 16 patients (72.7%). The median follow-up was 32.4 months. Univariate and multivariate analyses were performed to identify factors associated with tumor recurrence. Median ablation area was 36.6 mm(2) (30–50 mm(2)). The complication rate was 22.7%. No local recurrence was observed during follow-up. Disease-free survival was 20 months (4.8–55.2 months). Univariate analysis revealed that the number of liver metastases and node-positive primary tumors were associated with tumor recurrence. Multivariate analysis revealed that node-positive primary tumor was the only factor significantly associated with tumor recurrence (p = 0.049; odds ratio, 12; 95% confidence interval, 1–143). When performed with a 10-mm safety margin, surgical MWA can lead to acceptable oncological outcomes with low morbidity. Therefore, it represents a good option in selected patients with CLM.