Friedman, Sue

Abstract Detection of germline pathogenic Variants (PVs) in BRCA1, BRCA2, and other genes that significantly elevate lifetime breast cancer (BC) risk are indications for early initiation of intensive screening. BRCA1/2 PVs guidelines recommend that magnetic resonance imaging (MRI) screening begin at age 25 and mammography screening at age 30. However, pregnancy, breastfeeding, and the postpartum period may complicate adherence due to patient concerns about MRI contrast, radiation exposure, logistical barriers, and limited guidance on timing. The incidence of BC peaks approximately 5 years postpartum, especially among women with a positive family history, and early-onset cancers are frequently aggressive, exacerbating the effects of delayed detection. We assessed screening and counseling practices during reproductive periods among women with or at risk for PVs to identify knowledge gaps and opportunities to improve surveillance. We conducted an anonymous survey from March 2023 through January 2025 distributed by Facing Our Risk of Cancer Empowered (FORCE) and social media platforms. Data were collected through a secure REDCap instrument and summarized with descriptive statistics and logistic regression. The Mayo Clinic Institutional Review Board deemed the study exempt. Among the 537 respondents (median age 43 years; 88.5% U.S. residents; 87.5% White), 66.2% were parous and 61.8% knew their family history of BC during pregnancy. Most women reported receiving counseling on screening breast examination, mammography, and MRI; however, 74-77% received no specific guidance about screening before, during, or after pregnancy and weaning. At the time of the survey, 89.9% had undergone BC screening, including 66.2% with annual mammography and 53.1% with annual MRI. Yet during pregnancy and breastfeeding, 69% reported not being screened. Parous women were more likely than nulliparous women to report screening (96.9% vs 85.6%,p<0.0001) and regular mammography (76.4% vs 57.2%,p<0.0001). Screening during pregnancy and breastfeeding was more common among the BRCA1/2 carriers than among carriers of other PVs. Breastfeeding affected screening behavior in 32% of the BRCA1/2 carriers versus 10.9% of other PV carriers, yet only 5.1% of PV carriers stopped breastfeeding to undergo imaging. After their last birth, many women postponed screenings for more than 3 years and only 20.5% received a mammogram within a year of their delivery. Overall, 28.8% of participants reported a history of cancer, of which 66.2% was BC. Approximately 20% of breast cancers reported were diagnosed within 3 years postpartum, with 8.6% occurring during lactation. Despite high rates of BC screening, most high-risk women received little counseling about imaging during pregnancy and breastfeeding, potentially contributing to delayed surveillance at a time of heightened BC risk. These findings highlight the need for targeted counseling, scheduling strategies to support MRI or other imaging during and after pregnancy, and development of novel early-detection tools such as blood or breastmilk biomarkers. Citation Format: Laura M. Pacheco-Spann, Sue Friedman, Diane Rose, William D. Foulkes, Zhihui Fang, Lauren E. Haydu, Mark E. Sherman. Breast Cancer Screening During Reproductive Years in Women with Germline Pathogenic Variants: Gaps in Counseling and Practice [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: The Rise in Early-Onset Cancers—Knowledge Gaps and Research Opportunities; 2025 Dec 10-13; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(23_Suppl):Abstract nr A029.