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Purpose: To explore what extent of ablative margin depicted by computed tomography (CT) immediately after radiofrequency (RF) ablation is required to reduce local tumor progression (LTP) for colorectal cancer (CRC) lung metastases., Materials and Methods: This retrospective study was undertaken as a supplementary analysis of a previous prospective trial. Seventy patients (49 men and 21 women; mean age ± standard deviation, 64.9 years ± 10.6 years) underwent RF ablation for CRC lung metastases, and 95 tumors that were treated in the trial and followed up with CT at least 12 months after RF ablation were evaluated. The mean tumor size was 1.0 cm ± 0.5 cm. The ablative margin was estimated as the shortest distance between the outer edge of the tumor and the surrounding ground-glass opacity on CT obtained immediately after RF ablation. The impact of the ablative margin on LTP was evaluated using logistic regression analysis. Multivariate logistic regression analysis was also performed to identify the risk factors for LTP. The result was validated with multivariate logistic regression applying a bootstrap method (1,000 times resampling)., Results: The mean ablative margin was 2.7 mm ± 1.3 (range, 0.4-7.3 mm). LTP developed in 6 tumors (6%, 6/95) 6-19 months after RF ablation. The LTP rate was significantly higher when the margin was less than 2 mm (P = .023). A margin of <2 mm was also found to be a significant factor for LTP (P = .048) on multivariate analysis and validated using the bootstrap method (P = .025)., Conclusions: An ablative margin of at least 2 mm is important to reduce LTP after RF ablation for CRC lung metastases., (Copyright © 2022 SIR. Published by Elsevier Inc. All rights reserved.)

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. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Gemmete in this issue.

This study was undertaken to evaluate long-term results of radiofrequency (RF) ablation in patients with colorectal lung metastases and to stratify patients benefitting from lung RF ablation. Lung RF ablation was performed in 78 patients with 198 colorectal lung metastases. Safety, local tumor progression, and survival were evaluated retrospectively. The mean follow-up period after the 140 lung RF ablation sessions was 24.6+/-7.6 months. Pneumothorax and pleural effusion requiring chest tube placement occurred respectively in 18 (12.9%, 18/140) and 2 (1.4%, 2/140) sessions. The respective 1-, 3- and 5-year local tumor progression rates were 10.1% (95% CI, 2.9-17.3%), 20.6% (95% CI, 8.9-22.2%) and 20.6% (95% CI, 8.9-22.2%). The 1-, 3- and 5-year survival rates were 83.9% (95% CI, 75.2-92.7%), 56.1% (95% CI, 41.7-70.5%) and 34.9% (95% CI, 18.0-51.9%), with median survival time of 38.0 months. Univariate analysis revealed maximum tumor diameter of 3 cm or less, single-lung metastasis, lack of extrapulmonary metastasis and normal carcinoembryonic antigen (CEA) level as better prognostic factors. The latter two were significant independent prognostic factors. The 1-, 3- and 5-year survival rates were 97.7% (95% CI, 93.3-100%), 82.5% (95% CI, 68.2-96.8%) and 57.0% (95% CI, 34.7-79.2%) in 54 patients with no extrapulmonary metastases and 96.9% (95% CI, 90.8-100%), 86.1% (95% CI, 71.1-100%) and 62.5% (95% CI, 36.3-88.6%) in 33 patients with negative CEA levels. Lung RF ablation is a safe and useful therapeutic option. These identified prognostic factors will help to stratify patients who benefit from lung RF ablation.

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 (< or =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.