Prevalence of Germline Variants in Prostate Cancer and Implications for Current Genetic Testing Guidelines

Abstract

<div class="section"> <a class="named-anchor" id="ab-coi180119-1"> <!-- named anchor --> </a> <h5 class="section-title" id="d3987567e341">Question</h5> <p id="d3987567e343">What is the germline mutational landscape in unselected patients with prostate cancer, and do guidelines for genetic testing adequately identify patients at risk for aggressive disease? </p> </div><div class="section"> <a class="named-anchor" id="ab-coi180119-2"> <!-- named anchor --> </a> <h5 class="section-title" id="d3987567e346">Findings</h5> <p id="d3987567e348">This cross-sectional study of 3607 men with a personal history of prostate cancer found that 620 (17.2%) had a pathogenic germline variant, of which 229 (37%) did not qualify (at time of testing) for genetic testing per National Comprehensive Cancer Network recommendations. </p> </div><div class="section"> <a class="named-anchor" id="ab-coi180119-3"> <!-- named anchor --> </a> <h5 class="section-title" id="d3987567e351">Meaning</h5> <p id="d3987567e353">National Comprehensive Cancer Network guidelines and Gleason scores are not reliable for stratifying patients with prostate cancer for the presence or absence of pathogenic germline variants; simplification and expansion of testing guidelines will improve medical management of these patients. </p> </div><p class="first" id="d3987567e356">This cross-sectional study assesses the frequency and distribution of positive germline variants in patients with prostate cancer and evaluates the usefulness of current practice guidelines in recognizing individuals with prostate cancer who would benefit from diagnostic genetic testing. </p><div class="section"> <a class="named-anchor" id="ab-coi180119-4"> <!-- named anchor --> </a> <h5 class="section-title" id="d3987567e360">Importance</h5> <p id="d3987567e362">Prostate cancer is the third leading cause of cancer-related death in men in the United States. Although serious, most of these diagnoses are not terminal. Inherited risk for prostate cancer is associated with aggressive disease and poorer outcomes, indicating a critical need for increased genetic screening to identify disease-causing variants that can pinpoint individuals at increased risk for metastatic castration-resistant prostate cancer. </p> </div><div class="section"> <a class="named-anchor" id="ab-coi180119-5"> <!-- named anchor --> </a> <h5 class="section-title" id="d3987567e365">Objective</h5> <p id="d3987567e367">To identify positive (pathogenic, likely pathogenic, and increased risk) germline variants in a large prostate cancer cohort and to evaluate the usefulness of current practice guidelines in recognizing individuals at increased risk for prostate cancer who would benefit from diagnostic genetic testing. </p> </div><div class="section"> <a class="named-anchor" id="ab-coi180119-6"> <!-- named anchor --> </a> <h5 class="section-title" id="d3987567e370">Design, Setting, and Participants</h5> <p id="d3987567e372">Cross-sectional study of data from 3607 men with a personal history of prostate cancer who underwent germline genetic testing between 2013 and 2018 and were unselected for family history, stage of disease, or age at diagnosis. Referral-based testing was performed at a Clinical Laboratory Improvement Amendments/College of American Pathologists–certified diagnostic laboratory. All analysis took place between February 2017 and August 2018. </p> </div><div class="section"> <a class="named-anchor" id="ab-coi180119-7"> <!-- named anchor --> </a> <h5 class="section-title" id="d3987567e375">Main Outcomes and Measures</h5> <p id="d3987567e377">The frequency and distribution of positive germline variants, and the percentage of individuals with prostate cancer who met National Comprehensive Cancer Network (NCCN) guidelines for germline genetic testing. </p> </div><div class="section"> <a class="named-anchor" id="ab-coi180119-8"> <!-- named anchor --> </a> <h5 class="section-title" id="d3987567e380">Results</h5> <p id="d3987567e382">Of 3607 men (mean [SD] age at testing, 67 [9.51] years; mean age at diagnosis, 60 [9.05] years) with a personal diagnosis of prostate cancer who were referred for genetic testing, 620 (17.2%) had positive germline variants, of which only 30.7% were variants in <i>BRCA1/2</i>. Positive variants in <i>HOXB13</i>, a gene associated only with prostate cancer risk, were identified in 30 patients (4.5%). DNA mismatch repair variants with substantial known therapeutic implications were detected in 1.74% of variants in the total population tested. Examination of self-reported family histories indicated that 229 individuals (37%) with positive variants in this cohort would not have been approved for genetic testing using the NCCN genetic/familial breast and ovarian guidelines for patients with prostate cancer. </p> </div><div class="section"> <a class="named-anchor" id="ab-coi180119-9"> <!-- named anchor --> </a> <h5 class="section-title" id="d3987567e391">Conclusions and Relevance</h5> <p id="d3987567e393">Current NCCN guidelines and Gleason scores cannot reliably stratify patients with prostate cancer for the presence or absence of pathogenic germline variants. Most positive genetic test results identified in this study have important management implications for patients and their families, which underscores the need to revisit current guidelines. </p> </div>