Relative disclosure of information on hereditary cancer syndromes: A systematic review and meta-analysis

10592 Background: Evidence-based guidelines recommend that patients (probands) diagnosed with a hereditary cancer syndrome share the information with blood relatives as relatives can have 50% risk for harboring the same pathogenic mutation. This information offers the opportunity for relatives to undergo genetic counseling, genetic testing, early detection, and prevention of cancer. Limited literature on this topic suggests underutilization of recommended family member disclosure. We sought to evaluate rates of familial disclosure of hereditary cancer syndrome information in the first meta-analysis on this topic. Methods: We conducted a systematic review and meta-analysis in accordance with PRISMA guidelines (PROSPERO no.: CRD42020134276). We searched key electronic databases to identify studies evaluating hereditary cancer cascade relative disclosure. Eligible trials were subjected to meta-analysis. Results: Thirty studies met inclusion criteria. This review included 3,779 probands and 12,751 at-risk relatives. Among 12,751 included relatives, 72% (CI 64-79%) received information about the hereditary cancer syndrome identified in their family and 28% (CI 19-37%) underwent genetic testing. On meta-analysis, there was a higher rate of disclosure among female vs male relatives (79% [73% - 84%] vs 67% [57% - 75%]) and a higher rate among first-degree vs. second degree relatives (83% [77% - 88%] vs 58% [45 – 69%]). The data regarding the contribution of race/ethnicity to disclosure were limited and inconsistent, with two studies demonstrating non-White vs. White relatives being less likely to have results disclosure and two studies finding no correlation; however, both studies finding no difference were limited by small sample sizes. Finally, one study found that higher proband annual income was associated with improved familial disclosure. Conclusions: Despite a growing understanding of the importance of cascade genetic counseling and testing, probands do not disclosure information on hereditary cancer syndromes to most at-risk relatives. Very few relatives complete genetic testing, representing a critical missed opportunity for precision cancer prevention. Future studies are needed to elucidate barriers to hereditary cancer syndrome disclosure and create innovative strategies to facilitate this essential process.