Safety and efficacy of radiofrequency ablation for pulmonary metastases in metastatic colorectal cancer patients: A single center experience

141 Background: Radiofrequency ablation (RFA) has been increasingly used for the treatment of pulmonary metastases from several types of malignancies. Methods: A retrospective analysis was performed for the safety and efficacy of percutaneous RFA in patients with metastatic colorectal cancer between October 2016 and June 2019 as well as assessing prognostic factors of local tumor control. Results: RFA was carried out for 48 lung metastases in 31 consecutive colorectal cancer patients. Male was 17 patients (55%), and the median age at RFA was 61 years (range, 42-81). The mean diameter of metastases targeted for RFA was 12 mm (range, 4-32), and 17 tumors (35%) were located in a sub-pleural or deep position. Although five cases (10%) were failed due to immediate complications, there was no procedure-related death. In terms of immediate complication, a total of 12 cases (25%) had events including nine pneumothorax (percutaneous drain in four), one pleural effusion, and two hemoptysis (ICU care in one). Delayed complications were lung abscess and diaphragm injury in each one patient, respectively. At the time of analysis, the median follow-up duration from RFA was 12.0 months (interquartile range, 6.5-23.1). Only two patients (6%) died of disease progression, and 3-year overall survival rate was 85.5% (95% CI, 75.5-95.5). RFA site progression was observed in 11 patients (23%), and 1-year and 2-year progression-free survival rates were 71.5% (95% CI, 58.7-84.3) and 56.6% (95% CI, 42.6-70.6), respectively. Multivariate analysis showed that extra-pulmonary progression (hazard ratio 17.49; p = 0.023) was only one independent prognostic factor associated with RFA site progression after adjusting for confounding factors including sex, age, performance, tumor size, location, contact with the vessel, last chemotherapy response, and duration. Conclusions: RFA is a comparatively safe and effective option for the treatment of small-sized lung metastases; however, the control of extra-pulmonary metastases should be accompanied for effective local control.