Ablative therapies for colorectal liver metastases: a systematic review

Aim The standard treatment for colorectal liver metastases (CRLM) is surgical resection. Only 20-30% of patients are deemed suitable for surgery. Recently, much attention has focused on ablative therapies either to treat unresectable CRLM or to extend the margins of resectability. This review aims to assess the long-term outcome and complication rates of various ablative therapies used in the management of CRLM. Method A literature search was performed of electronic databases including Medline, Cochrane Collaboration Library and the National Library of Medicine's ClinicalTrials.gov. Inclusion criteria were ablation for CRLM with minimum 1 year follow-up and > 10 patients, published between January 1994 and January 2010. Results In all, 226 potentially relevant studies were identified, of which 75 met the inclusion criteria. Cryotherapy (26 studies) had local recurrence rates of 12-39%, with mean 1-, 3- and 5-year survival rates of 84%, 37% and 17%. The major complication rate ranged from 7% to 66%. Microwave ablation (13 studies) had a local recurrence rate of 5-13%, with a mean 1-, 3- and 5-year survival of 73%, 30% and 16%, and a major complication rate ranging from 3% to 16%. Radiofrequency ablation (36 studies) had a local recurrence rate of 10-31%, with a mean 1-, 3- and 5-year survival of 85%, 36% and 24%, with major complication rate ranging from 0% to 33%. Conclusion Ablative therapies offer significantly improved survival compared with palliative chemotherapy alone with 5-year survival rates of 17-24%. Complication rates amongst commonly used techniques are low.