Attitudes and engagement about cascade genetic testing among women diagnosed with cancer.

313 Background: Cascade testing in families with hereditary cancer syndromes is challenging because patients are responsible for engaging their relatives about test results and clinical support is limited. There are concerns that patient engagement with family members may not be well tailored to the clinical relevance of their test results, with particular concern about variants of uncertain significance (VUS). Methods: We selected patients from the Georgia California Genetic Linkage Initiative, which identified all patients diagnosed with cancer 2013-19 in the 2 states who linked to a germline genetic test. We surveyed 2100 women diagnosed with breast, ovarian or uterine cancer in 2018-19 in Georgia and California who reported a pathogenic variant (PV) that increases the risk of cancer on testing about 4 years after diagnosis and a comparable sample of 1250 women who reported a VUS-only result. The expected response rate from the cohorts is 55% (N=1900). We present preliminary results on patient attitudes about engagement with family and clinicians and behaviors related to their test results. Results: The 2 cohorts were comparable in age (mean 54 vs 58 for VUS, p<.001) and education (college graduate or more 52% vs 53% for VUS p=.235). The Table shows that for patients who reported a PV, belief in the utility of testing in family members was high. A substantial proportion reported that a genetic counselor encouraged them to talk to relatives and talked directly with relatives about testing. PV carriers informed most first-degree relatives about their test results. Patients who reported VUS only were less likely to endorse the utility of testing in relatives; less likely to report that a genetic counselor encouraged family engagement or engaged family directly about testing; and were less likely to have informed relatives about their test results. PV carriers with breast cancer were more likely than VUS-only carriers to receive bilateral mastectomy after diagnosis: PV high risk 88%, PV lower risk 55%, PV other 48%, VUS only 45% p<.001. Conclusions: Compared to patients with VUS-only test results, women with PVs on germline genetic testing after diagnosis of cancer had more positive attitudes about the utility of testing of family members, greater engagement with clinicians and family members about test results and greater uptake of prevention procedures. These findings suggest that engagement with family about genetic testing after cancer diagnosis matches the clinical relevance of the results. Patient attitudes and report of engagement about genetic test results. % Item PV N=596 VUS only N=166 Genetic test results are useful to my family 90 64 Wanted family members to get tested 84 46 Genetic counselor encouraged me to talk about results with family 73 46 Genetic counselor talked directly with family members about testing 56 38 % of first-degree relatives who were informed of patient test results, mean 88 65 p<.001 for all comparisons.