Implementation of systematic germline genetic testing (GT) for metastatic prostate cancer (mPC) patients at the Puget Sound VA prostate oncology clinic.

Abstract

1578 Background: There is increasing clinical relevance for GT in patients with mPC to evaluate the 2-fold possibilities of molecularly targeted therapies and implications for relatives. NCCN guidelines recommend GT for subsets of men, including those with mPC. While exciting, there are new logistical challenges around workflows for delivering GT services. We sought to address these challenges through a prospective pilot study designed to systematically deliver GT to all men with mPC receiving care at the Puget Sound VA prostate cancer (PUG-VA PC) Clinic. Our hypothesis was that systematic universal GT for men with mPC would identify similar prevalence rates of germline pathogenic/likely pathogenic variants (P/LPV) among veterans compared to previously reported cohorts. Methods: We conducted an IRB-approved, prospective trial testing feasibility of a systematic workflow to identify all veterans with mPC seen at PUG-VA PC Clinic between 11/2016-1/2020 to discuss and offer GT. A research coordinator pre-screened each clinic schedule to identify patients with mPC, notified the oncologist to discuss pretest education and GT with the patient at the appointment. Consenting patients provided a saliva sample same day in clinic for the CLIA-certified Color Genomics 30-gene cancer gene panel. Results were issued to patients and providers, and results were discussed by email and phone with a genetic counselor. Uptake of GT and prevalence of P/LPV was measured and compared to previously reported data from the retrospectively tested UW TAN cohort. χ2-test was performed. Results: 84% (190/227) of approached veterans with mPC consented and 80% (182/227) completed GT. 6.6% (12/182) of men were found to carry P/LPV in DNA repair genes: 3 in BRCA2, 2 in BRCA1, 4 in ATM, and 3 in CHEK2. Overall, 6.6% rate of P/LPV in DNA repair genes was comparable to the 8.8% previously reported in the UW TAN cohort (p = 0.69). Conclusions: Dedicated clinic-based strategies to offer and provide GT and services for veterans with mPC is feasible and results in high GT consent and uptake, especially with direct oncologist involvement. Proportion of consenting to proceed with GT was nearly identical to a referral-based specialty Prostate Cancer Genetics Clinic (Pouv, Sokolova, and Cheng, unpublished). The proportion of P/LPV in the PUG-VA PC population was comparable to a geographically similar retrospective cohort. Updated data, including detailed demographics and GT results, will be reported at final presentation.