Clinical

Neoplastic seeding after RF ablation tied to liver tumor differentiation

Last Updated: 2009-01-07 19:00:26 -0400 (Reuters Health)

NEW YORK (Reuters Health) - The extent of poor tumor differentiation is a risk factor for neoplastic seeding in patients who undergo radiofrequency (RF) ablation for hepatocellular carcinoma, Japanese researchers report in the December issue of the American Journal of Gastroenterology.

Senior investigator Dr. Masao Omata and colleagues at the University of Tokyo note that the reported rate of seeding in such patients may reach as high as 12.5%.

However, Dr. Omata told Reuters Health that this "seeding rate is too high...because the rate in subsequent studies, including ours, is 1 to 2%."

The investigators came to this conclusion after studying data on 1031 patients who underwent 1845 treatments of RF ablation. Over a median follow-up 35.3 months, 33 patients showed evidence of neoplastic seeding.

This amounted to an incidence of 3.2% per patient or 1.8% per treatment. Twenty-one of the cases occurred on the line of previous RF ablation needle insertion.

The median time until detection was 15.2 months and cumulative 1-year survival after detection was 86%, which declined to 47% after 2 years.

On multivariate logistic regression analysis, the team found that only the degree of poor differentiation was associated with the risk of neoplastic seeding. Surrogate markers for poor differentiation were larger tumors and elevated tumor marker levels.

In these circumstances, the researchers conclude that the indications for RF ablation "should be carefully considered."

Am J Gastroenterol 2008;103:3057-3062.