Clinical outcomes and prognostic factors of cone-beam CT-guided radiofrequency ablation for pulmonary metastases in colorectal cancer patients

Aim: Radiofrequency ablation (RFA) has been increasingly used for the treatment of pulmonary metastases in various malignancies. Methods: A retrospective analysis was performed to establish the safety and efficacy of cone-beam computed tomography (CBCT)-guided RFA in patients with metastatic colorectal cancer between 2016 and 2019, and the prognostic factors of local tumor control were assessed. Results: A total of 31 patients with colorectal cancer underwent 48 sessions of lung RFA. The mean diameter of metastases targeted for RFA was 11 mm (range: 4–32), and the RFA was technically successful in 43 sessions (90%). There were 14 complications (29%), the majority of which required no intervention, with no cases of mortality. The median follow-up duration from RFA in the surviving 29 patients was 18.0 months. Only two patients (6%) died of disease progression, and the 3-year overall survival rate was 91% (95% CI: 83–99). Local tumor progression (LTP) of the RFA site was observed in 27%, and the LTP-free survival rates at 1 and 2 years were 81% (95% CI: 70–82) and 64% (95% CI: 50–77), respectively. Multivariate analysis showed that the progression of extra-RFA sites and the presence of extrapulmonary metastasis were independent prognostic factors significantly associated with LTP at RFA site. Conclusion: Lung RFA using CBCT guidance is a comparatively safe and effective option for the treatment of lung metastases from colorectal cancer. However, the control of extrapulmonary metastases should be accompanied by combined or sequential systemic treatment and local treatment.