Evidence scarce to support RF ablation of colorectal CA metastases in the liver

NEW YORK (Reuters Health) - Radiofrequency (RF) ablation is widely used to treat hepatic metastases from colorectal cancer, but an American Society of Clinical Oncology evidence review warns there is no proof of the efficacy and efficiency of this approach.

In an October 18th online article in the Journal of Clinical Oncology, the authors point out that available evidence is from single-arm retrospective and prospective trials. There have been no published randomized controlled trials.

For their systematic clinical evidence review of the literature, Dr. Sandra L. Wong of the University of Michigan, Ann Arbor, and colleagues identified 73 relevant articles. All concluded with the statement that more prospective research is needed.

"What is apparent," Dr. Wong told Reuters Health, "is that resectable tumors should be considered for resection. However, this should not be construed as absolute proscription of RF ablation -- though there are no data to support its use in the setting of known extrahepatic disease."

Among the study's broad findings were that hepatic resection improves overall survival, particularly for patients with resectable tumors without extrahepatic disease.

Patient and tumor selection for RF ablation is discussed at length in the literature. For example, the highest ablation success rate is in patients with one or a few metastases less than 3 cm in diameter.

Reported 5-year survival rates ranged from 14% to 55%, and local tumor recurrence rates were 3.6% to 60%. Reported procedure-related mortality was no higher than 2% and the major complications rate was usually 6% to 9%.

Open, laparoscopic, or percutaneous RF ablation were the only methods reviewed. Cryotherapy and microwave ablation were not addressed.

"There is a compelling need for more research to determine the efficacy and utility of RF ablation to increase local recurrence-free, progression-free, and disease-free survival as well as overall survival for patients with hepatic metastases from colorectal cancer," the panel concludes.

"More work needs to be done to define how RF ablation should and should not be used," added Dr. Wong, "especially in the context of contemporary systemic chemotherapy options."

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