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A phase II trial of image-guided radiofrequency ablation of small breast carcinomas: Results of a multicenter study in Japan.

e11535 Background: Locally ablative therapy of early breast cancer represents the next frontier in the evolution of minimally invasive breast conservative therapy. We performed this Phase II trial to determine the efficacy and safety of Radiofrequency (RF) ablation of small localized invasive breast carcinomas as a multicenter study in Japan.


METHODS
Thirty-nine patients with core-biopsy proven invasive breast cancer, T<2 cm in diameter on ultrasound and MRI were enrolled in this trial. Under ultrasound guidance, the tumor and at least a 5mm margin of surrounding breast tissue were ablated with saline- cooled RF electrode followed by surgical resection. Pathologic and immunohistochemical stains were preformed to assess tumor viability.


RESULTS
Thirty-seven patients completed the treatment. The mean tumor size on ultrasound was 1.50 cm. The mean ablation time was 12 minutes using mean power of 80.0 watts. During ablation, the tumor became progressively echogenic that correspond with the region of sever electrocautery injury at pathologic examination. Of the 37 treated patients, H&E and NADPH viability staining was available for 27 patients and in 25 (92.5%), there was no evidence of viable cancer cells. H&E and or ssDNA staining were available for another 10 patients. In total, complete thermal injury to the target lesions was recognized in 33 of 37 treated patients (89.2%). No sever adverse effect on the skin and chest wall were noted.


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. We are planning a multicenter observation study for RF ablation of small breast carcinomas. No significant financial relationships to disclose.