Clinical Impact of a Rapid Genetic Testing Model for Advanced Prostate Cancer Patients

Abstract

Purpose: Genetic testing may alter clinical management for individuals with metastatic prostate cancer by identifying additional therapies. Traditional counseling models are unlikely to enable time-sensitive therapeutic decision-making. This study aimed to determine the feasibility and clinical impact of an alternative hereditary genetic testing model.

Materials and methods: As part of a multicenter, single-arm prospective trial, individuals with advanced prostate cancer were referred by their oncologist for testing of 14 genes associated with hereditary prostate cancer. Pretest education (brochure and video) was provided in the oncology clinic. Questionnaires assessing participant satisfaction with both pretest education and decision to undergo genetic testing were collected. A genetic counselor contacted participants by phone to obtain family history and discuss results. Medical records were queried to determine whether a change in clinical management was discussed.

Results: Of 501 participants consented to germline analysis, 51 (10.2%) had at least 1 pathogenic/likely pathogenic variant. Change in treatment was discussed with 22/48 (45.8%) of eligible participants who tested positive. Feasibility of this model was assessed by participant satisfaction and turnaround time. Average±SD satisfaction with the pretest education (15.5±2.2, 4-20 scale) and with the decision to undergo genetic testing (17.1±2.9, 4-20 scale) were both high. Results were returned 20 days (median) after sample collection.

Conclusions: Oncologist-initiated germline genetic testing in collaboration with a genetic counselor is a feasible approach to testing advanced prostate cancer patients with impactful clinical actionability. The testing model and educational material serve as resources to clinicians treating prostate cancer patients.

Keywords: delivery of health care; genetic counseling; genetic testing; patient education as topic; prostatic neoplasms.

Figure 1:. Mainstreaming Model.

Patients were approached by their treating oncologist in the clinic to undergo genetic testing. Pre-test education consisted of a written brochure and an eight-minute narrated video explaining benefits and risks of genetic testing. After consent, a blood or saliva sample was collected and sent to a commercial laboratory for analysis. When test results were available, a designated genetic counselor (GC) contacted the patient to collect family history and discuss results over the telephone. Each participant was provided a copy of their test result and a summary letter with the option to schedule an in-person consultation with the genetics service. This mainstreaming model of genetic testing took approximately three to four weeks to complete from the time of sample collection to return of results.

Figure 2:. Distribution of Test Results.

(A) Of the total participants (n=501) who underwent genetic testing, 378 (75.4%) were negative, 72 (14.4%) had a VUS, and 51 (10.2%) harbored a PV in a DNA repair gene included on the panel. Of the 51 participants who tested positive, 47 (92.2%) had a PV in a gene for which there is a targeted therapy either clinically available or available within the context of a clinical trial. 4 (7.8%) of the participants who tested positive had a PV in gene for which there is no current targeted therapy or clinical trial available. (B) Number of participants with PV in each gene.