Abstract OT1-3-01: Phase II study on radiofrequency ablation in stage 0 and I breast cancer without extensive intraductal components

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Abstract Background: Screening mammography makes it possible to identify small size of breast cancer (BC) and minimize surgical management. Previously we reported about a multi-center cohort study on radiofrequency ablation (RFA) in early breast cancer (ASCO2012 #1119). Although various devices and ablation procedure were attempted, 5-year’s recurrence-free survival of ipsilateral breast tumor was 96% in 425 cases of T1BC treated with RFA alone (the mean follow-up, 50 months). To validate complete pathological ablation in BC, we started a non-randomized phase II study in 2013 (UMIN000013836). Eligibility criteria: Unilateral BC patients with stage 0 (TisN0M0) or I (T1N0M0 or T1N1miM0) are eligible. Written informed consent is obtained. Tumor diameter of 2cm or less should be diagnosed by ultrasound and MR mammography. BC with diffuse calcification, extensive intraductal components, or multiple tumors is excluded. Methods: RFA is performed by Cool-tip RF ablation system (Covidien, USA). The needle electrode is inserted into the center of referent tumor under ultrasound guidance. The first ablation is started at an initial electrical power level of 5W for 1 min and the power is increased at 10W for 1 min. After then, it is increased in steps of 10W from every minute until rapid elevation of tissue impedance. The second ablation is allowed by physician’s discretion. One month later, ablated tissue is collected by core needle biopsy or vacuum-assisted breast biopsy. Cell viability is examined by central review of independent pathologists using tumor specimens stained with hematoxylin–eosin and nicotinamide adenine dinucleotide (NADH) diaphorase. In case of complete ablation, breast irradiation and adjuvant therapy will be performed. In case of incomplete ablation, partial mastectomy should be recommended. Aims: The primary endpoint is complete ablation rate. The secondary endpoints are deformity after RFA, relapse-free survival and overall survival for 10 years. Two-step design is used for statistical evaluation. Finally, 32 patients will be needed. Present accrual: As of April 2014, 16 patients were enrolled. One patient was ineligible because of macrometastasis in a sentinel node. Of 13 eligible patients who underwent pathological examination, one patient had viable cancer cells with NADH diaphorase staining. We also investigate optimal histological examination of cell viability and adequate image diagnosis after RFA. Citation Format: Shigeru Imoto, Shinji Nagamine, Shunichi Ito, Hitoshi Tsuda, Masayuki Yoshida, Mitsuhiro Tozaki, Satoshi Morita, Takayuki Ueno. Phase II study on radiofrequency ablation in stage 0 and I breast cancer without extensive intraductal components [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr OT1-3-01.