Ablative and catheter-delivered therapies for colorectal liver metastases (CRLM)

Colorectal liver metastases occur in a significant number of patients with bowel cancer. Only a small proportion of patients will be candidates for surgical resection and more than 50% of these will develop further metastases. Palliative chemotherapy has been the mainstay of treatment for the remainder of patients with unresectable disease. Toxicity is common and median survival is in the order of 18 months, although this has increased slightly with the addition of monoclonal antibodies and angiogenesis inhibitors. Targeted treatment of liver metastases with ablative or trans-arterial techniques allows localised, minimally invasive therapy without significant toxicity or morbidity. Ablative techniques include radiofrequency, microwave, laser and cryotherapy. Catheter-delivered trans-arterial treatments include conventional chemoembolisation, drug-eluting beads and selective internal radiation spheres. High intensity focussed ultrasound is also likely to play a significant role in the future. The combination of these treatment options with or without systemic chemotherapy may have a synergistic effect. This article will discuss the role and efficacy of each of these techniques.