Intra-Operative Electronic Brachytherapy in the Treatment of Early Stage Breast Cancer – A Multi-Center Trial, Technique and Preliminary Results

Abstract

To report on the technique of intra-operative electronic brachytherapy in a non-randomized multi-center study using a single fraction at the time of partial mastectomy and sentinel biopsy of axillary lymph nodes and early results, with side effects and complications. This Phase 4, single arm prospective non-randomized trial enrolled 1200 patients from May 2012 till July 2018. Twenty-seven National and International institutions participated in the trial for biopsy proven invasive ductal carcinoma and ductal carcinoma in situ who met the inclusion criteria, underwent partial mastectomy and sentinel node biopsy of axillary lymph nodes followed by a single fraction of 2000 cGy IORT to the lumpectomy cavity using Xoft system of electronic brachytherapy. 1200 patients received the prescribed dose of 2000 cGy to the lumpectomy cavity. 917 (76.4%) had invasive ductal carcinoma, 208 (17.3%) ductal carcinoma in situ, 39 (3.3%) other histology, and thirty-six patients had unknown histology. 79% of the patients were Caucasian, 7% African American, 7% Hispanic, and 7% other. 126 (10.5%) were staged as T1a disease, 349 (29.08%) T1b and 404 (33.66%) T1c. Estrogen receptor was positive in 93.3% of patients, 87% were progesterone positive, and all were BRCA negative. 14% of DCIS were Grade 1, 44% were Grade 2, and 42% were Grade 3. Seroma occurred in 33%, induration in 22%, and significant fibrosis in 21% of patients. 33/1200 (2.75%) patients developed ipsilateral recurrence. 9/1200 patients developed cancer in the contralateral breast primary versus metastatic. Only 1 patient with a recurrence, or new primary received whole breast irradiation following IORT. Early results of the single fraction of IORT using an electronic brachytherapy system applicator in the treatment of early stage breast cancer is safe with low morbidity, low local recurrence and excellent cosmetic results.