1561 Background: Proliferative breast lesions with atypia (atypical hyperplasia and lobular carcinoma in-situ (LCIS)) increase the risk of breast cancer (BC). Most cases are diagnosed in the context of an abnormal mammogram. Little is known about BC risk for patients with these lesions who are asymptomatic. Mammoplasty specimens allow us to study breast tissue in asymptomatic healthy women. We previously published the rate of atypia in the largest reported mammoplasty cohort. The aim of this study is to examine the risk of BC in the atypia cohort. Methods: Breast pathology reports were retrospectively reviewed for evidence of atypical ductal hyperplasia (ADH), atypical lobular hyperplasia (ALH) or LCIS in bilateral reduction mammoplasty specimens from five institutions within a single healthcare system between 1990 to 2017. Patients with prior or concurrent BC or prior atypia were excluded. Data was extracted from electronic medical records using natural language processing and manual review to assess subsequent risk of BC. Results: From our mammoplasty cohort of 4771 patients, 295 patients were found to have atypia (6.2%) at baseline. 40 of these patients were lost to follow-up and excluded from the study. For the remaining 255 patients, 13 had severe ADH bordering on ductal carcinoma in situ, 52 had LCIS, 119 had ALH, and 71 had ADH at baseline. The median age at baseline was 52.1 (range 17.9 – 74.3). With a median follow-up of 7.7 years, of the 255 patients 9 patients developed BC (8 invasive carcinomas, 1 ductal carcinoma in situ). 81.3% of the cohort did not receive chemoprevention. Only one patient out of the nine who developed BC received chemoprevention. The risk of developing BC among women with atypia at baseline was 0.5%, 2.9% and 4.1%, at 3, 5 and 10 years respectively. Conclusions: Patients with asymptomatic atypias found in reduction mammoplasty specimens appear to be at lower risk of developing BC than those diagnosed with atypia in the context of an abnormal mammogram. These results may provide guidance on how to manage this group of patients related to future screening and/or chemoprevention.
Breast Cancer Chemoprevention among High-risk Women and those with Ductal Carcinoma In Situ
