Oncologic outcomes and radiation safety of nipple-sparing mastectomy with intraoperative radiotherapy for breast cancer.

BACKGROUND: Nipple-sparing mastectomy combined with breast reconstruction helps to optimize the contour of the breast after mastectomy. However, the indications for nipple-sparing mastectomy are still controversial. Local radiation to the nipple-areola complex may play some roles in improving the oncological safety of this procedure.

METHODS: From January 2014 to December 2017, 41 consecutive patients who underwent nipple-sparing mastectomy combined with Intrabeam intraoperative radiotherapy to the nipple-areola complex flap and breast reconstruction were enrolled in this prospective study. The prescribed radiation dose at the surface of the spherical applicator was 16 Gy.

RESULTS: In eight cases, carcinomas were in the central portion of the breast. Partial necrosis of the nipple-areola complex occurred in three cases. Over 90% of patients reported "no or poor sensation" of the nipple-areola complex postoperatively. With a median follow-up time of 26 months, no recurrences or metastases were identified; however, breast-cancer mortality occurred in one patient. Pathologic evaluation of paraffin-embedded sections showed ductal carcinoma in situ in the remaining tissues deep to the nipple-areola complex flap in two patients. Although no further treatment was administered to the nipple-areola complexes postoperatively, no recurrences or metastases were identified 20 months and 24 months later, respectively. Optical microscopy and transmission electron microscopy revealed changes in some normal tissues immediately after Intrabeam intraoperative radiotherapy. Karyopyknosis were observed in gland tissues, and the collagenous fibers became sparse and arranged chaotically. As assessed by thermoluminescence, radiation doses at different sites in the nipple-areola complex flap varied considerably and were about 10 Gy at the areola surface. No Intrabeam intraoperative radiotherapy-related acute or chronic radiation injuries of the lung, heart or bone marrow were identified.

CONCLUSIONS: Our findings indicate that Intrabeam intraoperative radiotherapy during nipple-sparing mastectomy combined with breast reconstruction is safe and feasible.

TRIAL REGISTRATION: The current study was approved by the Ethics Committee of the First Affiliated Hospital of Guangzhou Medical University (registering order 201750). All participants gave their written informed consent.