Universal versus Guideline-Directed Germline Testing in Breast Cancer: Incremental Diagnostic Yield in a Predominantly Black Population.

backgroundThe American Society of Breast Surgeons recommends germline testing (GT) for all patients with a personal history of breast cancer (BC), citing concerns that guideline-based approaches may miss mutation carriers. We evaluated the incremental diagnostic yield of universal testing (UT) compared with National Comprehensive Cancer Network (NCCN)-guided testing in a predominantly Black population. PATIENTS AND

methodsWe performed an Institutional Review Board (IRB)-approved retrospective review of female patients with BC without prior GT evaluated at a community-based breast center between July 2024 and October 2025. Outcomes included testing uptake, GT results, pathogenic/likely pathogenic (P/LP) variant yield, and NCCN eligibility.

resultsAmong 170 patients, 94.1% were non-Hispanic Black. Of 147 patients who underwent GT, 6.1% harbored P/LP variants, 26.5% had variants of uncertain significance (VUS), and 67.4% tested negative. Most patients (91.2%) met contemporaneous NCCN criteria. P/LP detection rates were 6.0% in NCCN-eligible patients and 7.7% in non-eligible patients (p = 0.58). UT identified one additional BRCA2 mutation carrier outside NCCN criteria.

conclusionsIn this cohort, NCCN criteria captured the majority of patients undergoing GT, with mutation detection rates comparable to UT. The incremental diagnostic yield of UT was limited, identifying one additional mutation carrier. In resource-constrained settings, guideline-based testing may provide comparable clinical utility to universal testing approaches.