Hypofractionated radiation in secretory breast cancer: A case report.

Secretory carcinoma is a rare and indolent breast cancer with a lack of established treatment paradigms. We describe a case of a woman who underwent breast conservative therapy in the modern era. A 48 year old woman with a screen-detected left breast cancer was found to have early-stage secretory carcinoma after definitive breast conservation surgery. Further management with adjuvant radiation was recommended. After definitive breast conservative surgery, final pathology was notable for secretory breast carcinoma due to the immunohistologic characteristics of the tumor, ETV6-NTRK3 gene fusion, and histologic findings. After multi-disciplinary discussion, it was recommended that the patient proceed with adjuvant radiation. She was treated using a modestly hypofractionated regimen of 4256 cGy in 16 fractions. She tolerated the treatment well, developing only grade 1 radiation dermatitis. At 1 year follow-up she was clinically and radiographically free of disease. With a shift in management toward breast conservative therapy, defining the role of adjuvant radiation for secretory carcinomas in the modern era is of increasing importance. Modestly hypofractionated radiation is well-tolerated. Oncologic outcomes will be assessed with continued long-term follow-up.