Registry-based cohort study of 785 Black women diagnosed with invasive breast cancer at age ≤50 years (2005–2018) in Florida and Tennessee; 686 had confirmed germline testing for hereditary breast/ovarian cancer predisposition genes, comparing clinicopathologic features of hereditary vs. sporadic cases.
15.3% of tested women (n=105/686) carried a germline pathogenic/likely pathogenic variant (GPV): BRCA1 7.7%, BRCA2 4.5%, PALB2 0.9%, ATM 0.7%, others 1.5%. TNBC was seen in 75.5% of BRCA1 carriers vs. 23.6% of sporadic cases (p<.001). Over half of BRCA1-associated cancers (52.8%) were diagnosed at or below age 40. GPV frequency was 28.4% among TNBC cases and 10.6% among HR+/HER2− cases.
- Consent-based recruitment may introduce selection bias. - Small absolute numbers for many individual genes (e.g., PALB2 n=6, ATM n=5) limit precision of gene-level estimates. - Results are specific to young women (≤50 years) and may not generalize to older-onset breast cancer.
In young Black women with breast cancer, 1 in 7 carries a hereditary GPV—rates comparable to or higher than White populations—underscoring the need for universal genetic testing regardless of family history. Clinicians should not rely on family history alone to triage testing, as many carriers lack a reported family history.
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