Characteristics of probands with mutations predisposing to gynecologic cancers enrolled in a facilitated cascade testing protocol.

e13682 Background: We sought to evaluate the feasibility of obtaining genetic testing (GT) for first- or second-degree (1°, 2°) family members of a proband known to have actionable germline mutation associated with endometrial and/or ovarian cancer through a coordinated referral system. Here we characterize the initial probands and discuss the time frame of their enrollment in facilitated cascade testing (CT). Methods: Patients with pathogenic mutations associated with gynecologic cancers were determined from cancer genetics and gynecologic oncology clinics. Consenting patients completed a RedCap survey on personal cancer history and history of GT. They were then asked to contact 1° and/or 2° relatives regarding their GT results. Relatives were advised to contact our team. Relatives who consented to the study were referred for GT and contacted for follow up to ascertain whether they received GT and/or took action to reduce cancer risk. Results: From 3/2019- 1/2020, this study has accrued 39 probands. The median age was 39 years (range: 25-68). The most commonly expressed gene mutations were BRCA1 or BRCA2 (87.18%, n=34). Other mutations included BRIP1, MLH1, MSH2, MSH6, and PMS2. The majority (62%) of probands had no personal history of cancer. Among those who had a history of cancer (n=15), 80% had breast and/or ovarian cancer, and 80% reported their genetic mutation was discovered at or after the time of their cancer diagnosis. Median age at time of enrollment in CT was 49 years (range: 29-66) for patients with a history of cancer and 32 years (range: 25- 68) for those without, (p=0.009). Among all probands, the median time between mutation identification and enrollment in CT was 2 years (range=0 to 11). There was no significant difference in time between mutation identification and enrollment in CT when comparing those with and without cancer histories (p=0.5). Conclusions: These results suggest that patients with pathogenic mutations predisposing to gynecologic cancer are willing to undergo CT even if they have no personal history of cancer. Patients with a history of cancer tend to be older at time of enrollment in CT, likely because most discover their genetic mutation at or after the time of cancer diagnosis. With an average of 2 years elapsed between time of mutation identification and enrollment in CT, there is need for expansion of CT accessibility. Increased education and awareness among patients and providers in identifying those who may benefit from CT, screening, and risk reducing surgery to prevent cancer is needed.