A Phase II Trial of Image-Guided Radiofrequency Ablation of Small Invasive Breast Carcinomas: Use of Saline-Cooled Tip Electrode

Background Local ablative therapy of breast cancer represents the next frontier in the evolution of minimally-invasive breast conservation therapy. We performed this Phase II trial to determine the efficacy and safety of Radiofrequency (RF) ablation of small invasive breast carcinomas. Methods Seventeen patients with biopsy-proven invasive breast cancer, ≤ 1.5 cm in diameter were enrolled in this trial. Under ultrasound guidance, the tumor and a 5 mm margin of surrounding breast tissue were ablated with saline-cooled RF electrode followed by surgical resection. Pathologic and immunohistochemical stains were performed to assess tumor viability. We examined whether loss of ER, PR receptor and pancytokeratin expression following RF ablation would correlate with non-viability. Results Fifteen patients completed the treatment. The mean tumor size was 1.28 cm. The mean ablation time was 21 minutes using a mean power of 35.5 watts. During ablation, the tumors became progressively echogenic that corresponded with the region of severe electrocautery injury at pathological examination. Of the 15 treated patients, NADPH viability staining was available for 14 patients and in 13 (92.8%), there was no evidence of viable malignant cells. ER, PR expression and pancytokeratin immunohistochemistry analysis were unreliable surrogates for determining non-viability. Following RF ablation, 2 patients developed skin puckering. Conclusions RF ablation is a promising minimally invasive treatment of small breast carcinomas, as it can achieve effective cell killing with a low complication rate. Further research is necessary to optimize this image-guided technique and evaluate its future role as the sole local therapy.