On Jul. 30, 2026, a study led by Cedars-Sinai Health Sciences University investigators found that women who test negative for BRCA gene mutations may still be at greater risk of developing breast cancer than the general population. The findings, published in JAMA Network, highlight how strongly family history contributes to cancer risk.

An average woman has about a 13% chance of developing breast cancer during her lifetime, according to the National Cancer Institute. A BRCA1 or BRCA2 gene mutation raises breast cancer risk to 30%-70%, and BRCA testing is recommended for women with personal or family history of certain cancers, a known BRCA mutation in the family, or Ashkenazi Jewish ancestry.

Looking at the health records of almost 16,000 women who underwent BRCA testing in Ontario, Canada, from 2007 to 2016, investigators found that women who tested negative for a BRCA gene mutation still had a 25% lifetime risk of developing breast cancer. And lifetime risk for those with a variant of unknown significance, which means little is known about that particular variant, was 30%, according to the findings.

Each patient’s individual risk for breast cancer was substantially affected by their family history. Among women who tested positive for a BRCA mutation, breast cancer risk varied from roughly 56% to 86%, depending on the number of immediate family members who had breast or ovarian cancer, the study found.

In July, Cedars-Sinai opened the Cedars-Sinai Cayton BRCA Center to provide coordinated screening, guidance and treatment to patients with BRCA mutations.