Clinical features and risk factors of extrahepatic seeding after percutaneous radiofrequency ablation for hepatocellular carcinoma

Aim: To clarify the clinical features of and risk factors for extrahepatic seeding, a major complication following radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC). Methods: Our prospective database of 351 nodules in 257 patients with HCC who had undergone RFA between April 2001 and April 2008 was reviewed. The following variables were assessed to identify the risk factors for extrahepatic seeding: age, sex, viral markers, Child–Pugh class, tumor size, number of tumors, RFA indication (tumor size ≤3 cm, number of tumors ≤3), tumor biopsy prior to RFA, degree of histological differentiation, tumor markers, tumor location, number of sessions, and combined transcatheter arterial chemoembolization. Results: The median follow-up period was 36.5 months, during which the rate of seeding after was 5.1% and the 5-year cumulative seeding rate was 8.4%. The survival rate after neoplastic seeding was 21% at 5 years. Univariate analysis of the risk factors for neoplastic seeding showed significant differences in tumor size, RFA indication, subcapsular lesion, number of sessions, tumor biopsy prior to RFA, and des-gamma-carboxy prothrombin value. However, multivariate analysis showed that the only independent risk factor was RFA indication. Conclusions: The prognosis of patients with neoplastic seeding was poor. In particular, RFA performed for HCC not satisfying the RFA indication showed a high risk of seeding, and careful consideration should be given to the optimal treatment method and avoiding direct puncture of subcapsular tumors.