Contribution of mammography to breast cancer detection among pathogenic germline BRCA carriers by age and mutated gene.

10615 Background: Healthy carriers of pathogenic germline BRCA 1/2 (gBRCA) may choose between risk reducing mastectomy and intensive screening surveillance. Current international guidelines recommend both annual breast MRI and annual mammography. The aim of this study was to investigate the added contribution of annual mammography in gBRCA carriers to the annual breast MRI. Methods: A retrospective study from 2 large centers comprising gBRCA carriers who were diagnosed with breast cancer between 2000-2022 and were aware of their gBRCA status prior breast cancer diagnosis. Collected data included age at diagnosis, mutated gene and mode of breast cancer diagnosis (MRI, mammography, ultrasound US, or other means including clinical or incidental findings). Data on pregnancy and breastfeeding at the time of breast cancer diagnosis were also collected. Differences in the mode of diagnosis were analyzed by age (≤40y vs. >40y) and mutated gene (BRCA1 vs. BRCA2). Results: The cohort included 200 gBRCA carries: 134 (67%) BRCA1, 62 (31%) BRCA2 and 4 (2%) with both BRCA1 and BRCA2 mutations. The median age at the time of breast cancer diagnosis was 41 (24-88). Most cancers (68%) were diagnosed by MRI, followed by mammography (14.5%), US (7%) and other means (10.5%). While MRI was the most common diagnosis modality in both age groups, the distribution of mode of diagnosis was significantly different in younger women (≤40y) where breast cancer detection was more commonly by US or following clinical findings, compared to older women, p< 0.001 (see Table). Five women were pregnant and 9 women were breastfeeding at the time of breast cancer diagnosis, all age 40 or younger. Four (80%) of pregnant carriers and 5 (55.6%) of breastfeeding carriers were diagnosed by US. There was no difference in mode of diagnosis between BRCA1 to BRCA2 carriers, p=0.974. There were only 16 women under age 30 that were diagnosed with breast cancer, 2 (12.5%) of whom were diagnosed with mammography. Conclusions: MRI is the most common modality for breast cancer diagnosis in gBRCA carriers who were aware if there gBRCA prior breast cancer diagnosis. Annual mammography also has a meaningful role in this population. We did not identify a subgroup in which it could be omitted. The increased utility of US among younger women is attributed to reduced utilization of MRI/mammography during pregnancy and breastfeeding. This finding strengthens the role of US screening in gBRCA carriers who are not eligible for other methods of imaging. Table: see text