Radiofrequency Ablation, Electroporation, and Microwave Ablation

Image-guided ablation can provide effective local tumor control to selected patients with colorectal liver metastases (CLM) with less morbidity when compared to surgical resection, which allows for early initiation of adjuvant therapies and spares functional liver parenchyma, allowing repeated treatments at the time of recurrence. However, ablation does not consistently achieve oncological outcomes equal to surgery, which is currently considered the first-line local treatment modality in international guidelines. Ablation is indicated for a limited number (1–3 optimal, <5 preferable) of small-sized (<3 cm preferable) CLM. It has been recommended that ablation alone or ablation used in conjunction with resection as long as all visible diseases can be eradicated. A randomized controlled study suggested that radiofrequency ablation (± surgical resection) combined with systemic chemotherapy resulted in a survival benefit for patients with unresectable CLM compared to systemic chemotherapy alone. Several factors affect the outcomes of ablation, including but not limited to tumor size, number, location, minimal ablation margin, RAS mutation status, prior hepatectomy, and extrahepatic disease. Further understanding of the impact of tumor biology and advanced imaging guidance on overall patient outcomes might help tailor its application and improve outcomes of image-guided ablation in CLM patients.