Genetic Landscape of Male Breast Cancer

Male breast cancer (MBC) is now considered molecularly different from female breast cancer (FBC). Evidence from studies indicates that common genetic and epigenetic features of FBC are not shared with those diagnosed in men. Genetic predisposition is likely to play a significant role in the tumorigenesis of this rare disease. Inherited germline variants in BRCA1 and BRCA2 account for around 2% and 10% of MBC cases, respectively, and the lifetime risk of breast cancer for men harboring BRCA1 and BRCA2 mutations is 1.2% and 6.8%. As for FBC, pathogenic mutations in other breast cancer genes have also been recently associated with an increased risk of MBC, such as PALB2 and CHEK2 mutations. However, while multigene germline panels have been extensively performed for BC female patients, the rarity of MBC has resulted in limited data to allow the understanding of the magnitude of risk and the contribution of recently identified moderate penetrance genes of FBC for MBC predisposition. This review gathers available data about the germline genetic landscape of men affected by breast cancer, estimated risk associated with these genetic variants, and current guidelines for clinical management.

Reliability of Tumor Testing Compared to Germline Testing for Detecting BRCA1 and BRCA2 Mutations in Patients with Epithelial Ovarian Cancer

Background: BRCA 1/2 mutation status has become one of the most important parameters for treatment decision in patients with epithelial ovarian cancer (EOC). The aim of this study was to compare tumor DNA with blood DNA sequencing to evaluate the reliability of BRCA tumor testing results. Methods: Patients who were treated for EOC between 2003 and 2019 at the Medical University of Vienna and underwent both germline (gBRCA) and tumor (tBRCA) testing for BRCA mutations were identified. We calculated the concordance rate and further analyzed discordant cases. Results: Out of 140 patients with EOC, gBRCA mutation was found in 47 (33.6%) and tBRCA mutation in 53 (37.9%) patients. Tumor testing identified an additional 9/140 (6.4%) patients with somatic BRCA mutation and negative germline testing. The comparison of germline testing with tumor testing revealed a concordance rate of 93.5% and a negative predictive value of tumor testing of 96.0%. After BRCA variants of uncertain significance were included in the analysis, concordance rate decreased to 90.9%. Conclusion: Tumor testing identified the majority of pathogenic germline BRCA mutations but missed three (2.1%) patients. In contrast, nine (6.4%) patients harboring a somatic BRCA mutation would have been missed by gBRCA testing only.

Testing for mutations in BRCA1 and BRCA2 among ovarian cancer patients at a diverse academic medical center.

10588 Background: Testing for mutations in BRCA1 and BRCA2 is recommended for all women with ovarian cancer (OC), given important implications for treatment and prognosis. Despite this recommendation, studies show that only a small percentage of OC patients (pts) undergo genetic testing (GT). In this study, we evaluated rates of genetics referral, counseling and testing among OC pts at an academic medical center. Our goal was to identify factors associated with lower rates of GT. Given the large Black population at our center, we specifically wanted to evaluate the association between race and GT given limited existing data on this issue. Methods: Retrospective chart review was performed evaluating rates of referral and uptake for GT, and percentages of BRCA mutation carriers among pts with OC diagnosed and treated at Emory’s Winship Cancer Institute between 2008 and 2018. Associations between age, race, histology, family history (FH), performance status, provider characteristics and genetics referral and testing were evaluated using logistic regression models. Results: Of the 171 pts who met inclusion criteria, the majority were age 55 or older (62%) with high grade serous carcinoma (60.8%). Pts were predominantly Caucasian (59.4%), followed by Black (29.1%), Asian (10.3%) and Hispanic (1.2%). Overall, GT rates were low with 44.7% of pts referred for genetic counseling and 39.8% receiving testing. Among pts who did receive GT, the percentage of deleterious BRCA1 and BRCA2 mutations identified was 11% and 8.8% respectively. Variables correlating with higher likelihood of genetics discussion, referral and testing included serous histology (50% vs 23.9% non-serous, p < 0.001), Caucasian or Asian race (87.5% Asian, 58.8% Caucasian vs 42.2% Black, p = 0.003) and seeing a medical oncologist (67.5% vs 44.7% seeing gynecologic oncologist alone, p = 0.004). Notably, while fewer Black women were referred for GT (25.9% vs 74.1% Caucasian), those that did undergo GT were found to have higher rates of BRCA1 and BRCA2 mutations when compared to Caucasian pts (22.2% vs 8.2% BRCA1; 11.1% vs 6.0% BRCA2). Pts with a FH of OC were more likely to undergo GT (69.2% vs 37.9%, p = 0.027), and pts with a FH of breast cancer were more likely be referred for testing (57.1% vs 39.6%, p = 0.042), suggesting that FH impacted referral patterns. Conclusions: The rates of GT among OC pts at our institution were lower than expected despite the broad recommendation for GT in this population. It is imperative to improve access to GT for all OC pts regardless of FH, and in particular among Black pts given the higher rates of BRCA mutations in this population. Pts and providers must work together to overcome barriers to genetics referral and testing in order to improve GT rates and clinical outcomes. Further research is needed to design interventions that may help improve adherence to this important recommendation in the future.