Counseling experience with incidental cancer genes in expanded carrier screening

To examine counseling experience with incidental cancer genes in expanded carrier screening (ECS). ECS identifies couples at risk for transmitting a genetic condition to their offspring. While carriers for most genes on ECS do not experience symptoms, mutations in certain genes, such as ATM and NBN, may predispose patients to an increased risk for cancer (IRC). We analyzed Counsyl’s counseling experience to determine whether counseling patterns differed in patients with IRC. Our analysis included 152,973 individuals who had undergone routine carrier screening of up to 108 genes using Counsyl’s results workflow: patients were contacted in accordance with our privacy policy to view their results online with tailored informational videos and request genetic counseling (GC). GCs are available on-demand or by appointment. Consult rates were compared among carriers of mutations in IRC genes (ATM and NBN) and non-IRC genes. The 13 genes with fewer than 10 observed carriers were omitted from the analysis. Carriers within at-risk couples were also excluded. IRC genes were determined based on 2017 National Comprehensive Cancer Network guidelines. ATM and NBN carriers were significantly more likely to pursue GC than carriers of non-IRC genes. Specifically, 32% of NBN and 27% of ATM carriers pursued GC as compared to the non-IRC average of 20% (p=0.0086). We observed no significant preference for on-demand vs. scheduled consultation as 45% of ATM and 56% of NBN carriers pursued on-demand GC, compared to 48% amongst non-IRC gene carriers (p > 0.05 in both cases). Furthermore, median consult times across all Counsyl-facilitated GC sessions for ATM (13 minutes) and NBN carriers (10 minutes) were not significantly different from the overall median consult time (10 minutes; p > 0.05 in both cases). Carriers of IRC genes are more likely to seek GC, suggesting that personal health implications are an important determinant of patients’ desire for additional information. Clinicians should also consider having GC resources readily available to provide support for carriers with IRC.