Changes in Respiratory Function over Time after Radiofrequency Ablation for Lung Tumors

Purpose: To investigate changes in respiratory function after radiofrequency ablation for lung tumors. Material and Methods: Data from 21 patients who underwent respiratory function tests before radiofrequency ablation, during the early period (20-57 days; median, 34 days), and during the late period (104-692 days; median, 264 days) after lung radiofrequency ablation were retrospectively assessed. The index tumors included 10 primary lung cancers and 11 metastatic lung tumors, with a median tumor size of 12 mm (range, 4-21). Seventeen patients had a history of smoking, and the median Brinkman Index was 500 (range, 0-1,200). Percentage changes in vital capacity and forced expiratory volume in 1 s relative to baseline values were calculated and compared using the Wilcoxon signed-rank test. Risk factors for decreased vital capacity and forced expiratory volume in 1 s were examined by univariate analysis using the Mann-Whitney U test. Results: All radiofrequency ablation procedures were completed as planned. Vital capacity and forced expiratory volume in 1 s showed significant decreases to 98.0% (p = 0.048) and 96.8% (p = 0.048), respectively, in the early period, but recovered to 100.2% (p = 0.89) and 98.1% (p = 0.28), respectively, in the late period. Forced expiratory volume in 1 s decreased significantly in the early period among patients with a Brinkman Index >500 (98.9% for Brinkman Index ≤500 and 91.2% for Brinkman Index >500, p = 0.002). Conclusions: Respiratory function decreased temporarily within 2 months after lung radiofrequency ablation but recovered several months thereafter. Caution is needed because forced expiratory volume in 1 s tends to decrease in the early period after radiofrequency ablation in patients with a smoking history and a Brinkman Index >500.