Risk factors for local progression after percutaneous radiofrequency ablation of lung tumors: evaluation based on a preliminary review of 342 tumors

BACKGROUND: The purpose of the study was to retrospectively evaluate the risk factors for local progression after percutaneous radiofrequency (RF) ablation of lung tumors. METHODS: The study included 128 patients (77 men, 51 women; mean age, 61.3 years) with 342 tumors (25 primary and 317 metastatic lung neoplasms; mean long-axis diameter, 1.7 cm) treated with RF ablation. The overall primary and secondary technique effectiveness rates were estimated using Kaplan-Meier analysis. Multiple variables were analyzed using the log-rank test, followed by multivariate multilevel analysis to determine independent risk factors for local progression. The primary and secondary technique effectiveness rates were again estimated when considering only tumors without independent risk factors. RESULTS: The median follow-up period was 12 months (range, 6-47 months). The overall primary and secondary technique effectiveness rates were 72% and 84% at 1 year, 60% and 71% at 2 years, and 58% and 66% at 3 years, respectively. Larger tumor size (hazard ratio [HR], 1.97; 95% confidence interval [95% CI], 1.47-2.65; P < .00001) and the use of an internally cooled electrode (HR, 2.32; 95% CI, 1.10-4.90; P = .027) were assessed as independent risk factors for local progression. The primary and secondary technique effectiveness rates when considering tumors smaller than 2 cm and treated with a multitined expandable electrode were 89% and 89% at 1 year and 66% and 78% at 2 years, respectively. CONCLUSIONS: Larger tumor size and the use of an internally cooled electrode were independent risk factors for local progression after RF ablation of lung tumors.