Abstract P6-08-20: Cancer risk management and family sharing of genetic test results among women with inherited breast cancer genes

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Abstract Introduction: Identification of inherited breast cancer (BC) risk through genetic testing (GT) may guide button. Abstracts received without a properly medical care, which can be amplified by sharing test results with relatives. Among women with a completed Disclosure Declaration will not be pathogenic/likely pathogenic (P/LP) variant in an inherited BC gene, we sought to compare cancer risk considered. The size limit for the abstract (including management (CRM), as well as family sharing (FS) practices and family testing (FT) rates across genes. Methods: Female participants with a P/LP variant in BRCA, PALB2, CHEK2, or ATM were surveyed about CRM and FS/FT practices Frequencies of CRM (i.e., screening and/or risk-reducing surgery), and FS/FT rates were compiled and compared. Descriptive statistics, bivariate analyses, and non-parametric tests were performed to assess for associations. Results: The 238 participants with P/LP variants were as follows: 186 BRCA, 28 PALB2, 15 CHEK2, and 9 ATM. Median age of participants was 54 and most were non-Hispanic white (89%) with a prior cancer diagnosis (59%). Rates of risk-reducing mastectomy (RRM; defined as at least one breast removed prophylactically regardless of a prior BC diagnosis) was 65.1% among BRCA carriers, with lower rates among PALB2, CHEK2, and ATM carriers (32.1%, 33.3%, and 33.3%, respectively). Rates of risk-reducing salpingo- oophorectomy (RRSO) were appropriately higher among BRCA carriers (89.8%), but were also relatively common among PALB2, CHEK2, and ATM carriers (32.1%, 33.3%, and 66.7%, respectively). Rates of FS and FT were significantly higher in relatives of BRCA carriers compared to others (p=.003; p<.0001), with higher rates among third- compared to second-degree relatives (additional gene-specific rates outlined in Table 1). No significant differences were found between BRCA carriers versus other carriers in terms of insurance, employment, income, house size, education, race/ethnicity, cancer status, and/or involvement of a genetic healthcare provider (all p>0.05). Conclusion: Our results suggest that adherence to CRM for BRCA carriers is appropriately high. However, RRM among those with PALB2, CHEK2, and ATM P/LP variants are also frequently observed, despite the lack of practice guidelines to recommend RRM. Even more concerning is the appreciable RRSO rates in the absence of practice guidelines or data to confirm high ovarian cancer risk. Thus, our data suggest that many patients with P/LP variants in genes other than BRCA receive surgeries for which guidelines are lacking. These efforts highlight the tremendous need to promote risk appropriate care and reduce over-treatment among these individuals. Furthermore, reasons for lower FS and FT rates among women with P/LP variants in genes other than BRCA should be evaluated in future studies. Ultimately, as more data to refine cancer risks and management are generated across these other inherited BC genes, strategies are needed to improve FS and FT among at-risk relatives and amplify testing benefits. Table 1: Average percent of FS and FT rates among relatives across genes BRCA PALB2 CHEK2 ATM N = 186 N = 28 N = 15 N = 9 Aware Tested Aware Tested Aware Tested Aware Tested First-degree 81.0% 38.9% 74.5% 27.7% 71.6% 26.8% 78.3% 23.3% Second-degree 56.4% 11.5% 35.2% 6.3% 41.1% 7.3% 26.2% 3.2% Third-degree 60.7% 13.3% 46.2% 5.8% 58.2% 5.1% 39.3% 6.6% Female 69.9% 30.6% 63.3% 22.6% 57.6% 13.7% 44.6% 13.6% Male 60.3% 10.8% 43.9% 6.1% 52.2% 9.9% 47.4% 7.6% Citation Format: Tuya Pal, Anne Weidner, Ann Tezak, Kate Clouse, Deborah Cragun. Cancer risk management and family sharing of genetic test results among women with inherited breast cancer genes [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-08-20.