Impact of breast density on the efficacy of radiofrequency ablation in early-stage breast cancer

Background Radiofrequency ablation (RFA) is a minimally invasive technique used to treat small breast tumors by delivering high-frequency current through a needle electrode under ultrasound guidance. In Japan, RFA became insurance-covered in 2023 as a local treatment for early-stage breast cancer. Methods We retrospectively analyzed data from patients who underwent RFA at our institution between February 2016 and March 2025. Breast density was classified into four categories based on the Breast Imaging Reporting and Data System. Associations between breast density and RFA parameters, including ablation temperature, duration, and impedance, were evaluated. Results RFA was performed on 50 breasts in 49 female patients. The mean peak ablation temperature after break was 81.0 ± 8.0 °C. A higher breast density was significantly associated with higher temperature. The mean ablation time until break was 446 ± 139 s, with a trend toward longer durations in denser breasts. The mean initial and final impedance values were 208 ± 72.3 Ω and 161 ± 66.5 Ω, respectively. Fat-rich breasts exhibited significantly higher impedance at both time points. Conclusion Fatty breast tissue was associated with higher impedance, lower peak temperatures, and shorter ablation times, potentially resulting in insufficient ablation. Breast density should be considered when planning RFA to ensure effective treatment.