Neoplastic seeding after radiofrequency ablation for hepatocellular carcinoma

BACKGROUND: Neoplastic seeding reportedly occurs in up to 12.5% of patients treated with radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC). The aim of this study is to assess the incidence, risk factors, and prognosis of neoplastic seeding after RFA among a large number of patients with a long-term follow-up. METHOD: From February 1999 to December 2004, 1,031 patients underwent a total of 1,845 treatments with RFA for a total of 3,837 HCC nodules. The following variables were assessed to elucidate the risk factors of neoplastic seeding: age, sex, positivity for viral markers, tumor size, number of tumor nodules, number of RFA sessions, tumor location, percutaneous biopsy prior to RFA, alpha-fetoprotein (AFP), des-gamma-carboxy prothrombin (DCP) and lens culinaris agglutinin-reactive fraction of AFP (AFP-L3) levels, and the degree of tumor differentiation. RESULTS: Neoplastic seeding was detected in 33 patients (3.2% per patient) at intervals of 4.8-63.8 (median, 15.2) months after RFA. On multivariate logistic regression analysis, only the poor differentiation degree was associated with the risk of neoplastic seeding (P = 0.012). Of tumor factors, tumor size, and AFP, DCP, and AFP-L3 levels were significantly associated with the poor differentiation degree. The cumulative survival rates 1 and 2 yr after the detection of neoplastic seeding were 86% and 47%, respectively. CONCLUSION: Poor differentiation degree was the risk factor of neoplastic seeding after RFA for HCC. The surrogate markers for poor differentiation degree were larger tumor size and elevated tumor marker levels. Indication for RFA should be carefully considered for HCC patients under these conditions.