Increased BRCA1/2 Testing May Improve Patient Outcomes

The current rate of BRCA1/2 testing for patients with newly diagnosed HER2-negative breast cancer is only 68% in the United States, according to data presented at the 2023 Miami Breast Cancer Conference.

BRCA1 and 2 are genes that help repair damaged DNA, a vital tool for combatting cancerous tumors. When individuals have a mutation in either of these genes, they may have an increased risk of several types of cancer, but it is named for its association to breast cancers, with the BR and CA indicating the first two letters of the words breast and cancer. The mutations are also linked to ovarian cancer, prostate cancer and pancreatic cancer.

According to the National Cancer Institute, 13% of women with unmutated BRCA1/2 genes will develop breast cancer, while 55% to 72% of women with a harmful BRCA1 variant and 45% to 69% of women with a harmful BRCA2 variant will develop breast cancer.

Adult patients with newly diagnosed stage 1, 2 or 3 HER2-negative resected breast cancer in active treatment were included in the study’s data analysis. A total of 395 patients were retrospectively enrolled, then divided into a group of 199 patients with hormone receptor (HR)-positive disease and 189 patients with triple-negative disease.

A total 68% patients with HER2-negative breaast cancer had documented BRCA1/2 testing. Additionally, 61% (122) of the HR-positive group and 74% (139) of the triple-negative group were tested.

Of the entire HER2-negative group, 68% (267) had documented BRCA1/2 testing. Additionally, 61% (122) of the HR-positive group and 74% (139) of the triple-negative group were tested.

Patients who had received BRCA1/2 testing were younger and more likely to be premenopausal than untested patients. Among premenopausal women, testing rates were 89% for HER2-negative disease, 92% for HR-positive and 87% for triple-negative patients. These numbers fell to 61%, 51% and 70% for HER2-negative, HR-positive and triple-negative disease, respectively, for postmenopausal patients.

Those with HR-positive disease were not only less likely to be tested for BRCA1/2 mutations, but were found to also be less likely to receive diverse testing for those mutations. The highest proportion of tests for all groups was through germline testing, which are DNA tests like blood tests or cheek swabs, as well as the current standard for BRCA mutation testing. Patients with triple-negative disease were the most likely to be tested for mutations on multiple sample types, such as tumors samples or circulating tumor DNA tests.

Race and ethnicity are contributing risk factors to BRCA mutations, with those most at risk being members of the Ashkenazi Jewish population as well as Icelandic and Norwegian peoples, and the majority of patients enrolled in this study were white. Patients in the Asian and other categories had the highest rates of testing in this study, but this is likely due to the extremely small sample sizes in these groups.

Study authors concluded by saying, “efforts should focus on increasing adoption of BRCA1/2 testing for all eligible patients to enhance adherence to guideline recommended precision medicine options and subsequent outcomes.”

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