Microwave Ablation in the Liver: An Update

Hepatocellular carcinoma (HCC) and secondary hepatic malignancies, most often arising from colorectal cancer, are a leading cause of morbidity and cancer-related deaths worldwide. In lieu of first-line surgical resection, which is precluded in more than 75% of cases due to underlying comorbid conditions or locally advanced disease, several minimally-invasive transarterial and thermal ablation procedures have emerged as safe and effective alternative therapies in select patients. Among the thermal ablative techniques, microwave ablation (MWA) has become the preferred treatment modality because of its operational convenience and superior heating profile, allowing for larger ablation zones and reduced treatment times while maintaining high technical success rates. To date, MWA has been demonstrated to provide equivalent, and in some cases improved, clinical outcomes compared to radiofrequency ablation (RFA) in patients with inoperable HCC or oligometastatic disease. Active areas of investigation include the comparison of MWA and transarterial therapies, such as transarterial chemoembolization (TACE), as well as combined multimodality therapies. Here we review the emerging topic of MWA for the treatment of hepatic malignancies by examining staging and treatment strategies, available technologies, procedural protocol and technique, and clinical outcomes.