Radiofrequency Ablation for the Treatment of Unresectable Lung Metastases in Patients with Colorectal Cancer: A Multicenter Study in Japan

Purpose: Results after lung radiofrequency (RF) ablation were retrospectively evaluated to determine whether lung RF ablation is an effective therapeutic option for the treatment of unresectable lung metastases from colorectal cancer. Materials and Methods: Seventy-one patients with 155 unresectable colorectal lung metastases underwent computed tomography (CT)-guided percutaneous RF ablation at four institutions. The maximum tumor size was 3 cm or less in 61 patients and 3.1-6.0 cm in 10 patients (range, 0.5-6.0 cm; mean, 2.4 cm ± 1.3). A single tumor was treated in 35 patients and multiple tumors in 36 patients. Extrapulmonary metastases were found in 30 patients. Follow-up with serial CT and positron emission tomography scans was performed from 4 to 42 months after RF ablation (mean, 19 months). Primary end point in this study was patient survival, and secondary end points were evaluation of safety of lung RF ablation and intrapulmonary recurrence. Results: Pneumothorax developed in 26 (37%) patients, and a chest tube was placed in 14 (20%) of them. Empyema developed in one (1%) patient. Thirty-three (47%) patients developed intrapulmonary recurrence and 19 (58%, 19/33) of them received repeat lung RF ablation. The estimated 3-year survival rate was 46% for all patients. Extrapulmonary metastasis, tumor size, and the carcinoembryonic antigen level were significant prognostic factors in the univariate analysis. The first two factors were significantly independent prognostic factors in the multivariate analysis. Thirty-six patients with small lung metastases (≤3 cm) and no extrapulmonary metastases had a 3-year survival rate of 78%. Conclusions: Lung RF ablation is a safe and effective treatment in selected patients with unresectable lung metastases from colorectal cancer.