Clinical presentation, national practice patterns, and outcomes of breast adenomyoepithelioma.

Breast adenomyoepithelioma (AME) is a rare tumor with the published literature mainly in the form of case reports. Thus, there is currently only limited published data to guide evidence-based management. We sought to use a large, contemporary US database to evaluate how these patients are managed and describe expected outcomes. The National Cancer Database was queried (2004-2013) for women with AME. Statistics included multivariable logistic regression, Kaplan-Meier analysis to evaluate overall survival (OS) and Cox proportional hazards modeling. Overall, 110 patients were analyzed. At diagnosis, the median age was 67 years and the median tumor size was 2.0 cm. All but four patients had node-negative disease. A majority (55%) of tumors were estrogen receptor negative, and only one was positive for HER2/neu. The most common surgical procedure was lumpectomy (60%); a minority (10.9%) of subjects underwent complete axillary nodal dissection, with one-quarter not undergoing pathologic nodal sampling. Chemotherapy, hormonal therapy, and radiotherapy were utilized in a minority of patients (26%, 8%, and 36%, respectively), and none were associated with OS. At median follow-up of 52 months, the 5-year OS for the entire population was 74.4%. Disease-related characteristics and practice patterns are described for AME, the largest study of this rare tumor to date. Resection is the most important aspect of management, and based on this dataset the low rate of nodal involvement suggests that in some cases nodal sampling could be safely omitted. Adjuvant therapy may be considered on a case-by-case basis. Taken together, these data provide valuable insight into a rare neoplasm that may better inform management of these patients.