A cohort study of 2,401 women with breast cancer found that 4.8% carried pathogenic or likely pathogenic BRCA1 or BRCA2 variants. Testing was performed in two accredited laboratories with a 155-gene panel, and patients underwent germline testing using blood, buccal, or saliva samples.

Patients were diagnosed with stage 0 to stage IV breast cancer between July 2020 and October 2023 at two City of Hope sites in Southern California. The median age at diagnosis was 54 years. Variants were classified according to American College of Medical Genetics and Genomics criteria. Sixteen of 116 patients aged 60 years or older carried BRCA1 or BRCA2 variants.

Prevalence varied across race and ethnicity, with 3% of Hispanic patients carrying BRCA1 variants compared with 2% of non-Hispanic patients. Hispanic patients were more than twice as likely to carry BRCA1 than BRCA2. Among Black patients, 8% carried either a BRCA1 or BRCA2 variant. In White patients, the prevalence was 5%. Six variants identified in the study had been previously reported in Hispanic families, consistent with known founder mutations.

“Over time, these barriers have been broken down. The cost of germline testing has become less cost prohibitive, and direct to consumer testing is readily available and has heightened the awareness and appreciation for this information,” said Joanne E. Mortimer, MD, of City of Hope Comprehensive Cancer Center.

The researchers noted several limitations. The study did not assess whether genetic testing results influenced treatment decisions or led to family testing. Selection bias was possible because patients had to provide consent to participate, which could affect the representativeness of the findings.

The investigators stated that knowledge of BRCA1 and BRCA2 status informs treatment decisions at all stages of breast cancer care, including surgical planning, adjuvant therapy, and advanced disease management. They suggested that universal testing should be considered, particularly for patients from minoritized racial and ethnic groups. The study was funded by the National Cancer Institute, and some researchers disclosed consulting fees or honoraria.

Full disclosures can be found in the published study.

Source: JAMA Network Open