Three-year Survival Rate after Radiofrequency Ablation for Surgically Resectable Colorectal Lung Metastases: A Prospective Multicenter Study

Background: Although radiofrequency ablation (RFA) is widely performed for the treatment of colorectal cancer (CRC) lung metastases, its efficacy for candidates with surgically resectable disease is unclear. Purpose: To evaluate the prognosis after RFA in participants with resectable CRC lung metastases. Materials and Methods: For this prospective multicenter study (ClinicalTrials.gov identifier: NCT00776399), participants with five or fewer surgically resectable lung metastases measuring 3 cm or less were included. Participants with CRC and a total of 100 lung metastases measuring 0.4-2.8 cm (mean, 1.0 cm +/- 0.5) were chosen and treated with 88 sessions of RFA from January 2008 to April 2014. The primary end point was the 3-year overall survival (OS) rate, with an expected rate of 55%. The local tumor progression rate and safety were evaluated as secondary end points. The OS rates were generated by using the Kaplan-Meier method. Log-rank tests and Cox proportional regression models were used to identify the prognostic factors by means of univariable and multivariable analyses. Adverse events were evaluated according to the Common Terminology Criteria for Adverse Events, version 3.0. Results: Seventy participants with CRC (mean age, 66 years +/- 10; 49 men) were evaluated. The 3-year OS rate was 84% ( 59 of 70 participants; 95% confidence interval [CI]: 76%, 93%). In multivariable analysis, factors associated with worse OS included rectal rather than colon location (hazard ratio [HR] = 7.7; 95% CI: 2.6, 22.6; P<.001), positive carcinoembryonic antigen (HR = 5.8; 95% CI: 2.0, 16.9; P =.001), and absence of previous chemotherapy (HR = 9.8; 95% CI: 2.5, 38.0; P<.001). Local tumor progression was found in six of the 70 participants (9%). A grade 5 adverse event was seen in one of the 88 RFA sessions (1%), and grade 2 adverse events were seen in 18 (20%). Conclusion: Lung radiofrequency ablation provided a favorable 3-year overall survival rate of 84% for resectable colorectal lung metastases measuring 3 cm or smaller. (C) RSNA, 2020.