According to a new study, women with a family history of breast cancer may still have a greater risk of developing the disease, even if they test negative for gene mutations. BRCA1 and BRCA2 gene testing is often recommended for women with a personal or family history of cancers. The American Cancer Society indicates that up to 10% of breast cancer cases are hereditary due to family gene changes.

Women with BRCA1 or BRCA2 gene changes face a higher risk of breast cancer, may develop cancer at a younger age, and have an increased risk of other cancers, such as ovarian cancer.

A study led by Cedars-Sinai Health Sciences University suggests that individuals with a family history, who test negative for mutations, still face a greater lifetime risk of breast cancer. Lead author Fahima Dossa, a surgical oncologist at Cedars-Sinai Cancer, noted that while testing negative may be reassuring, women with a strong family history of cancer often undergo this test.

Cancer risk is elevated for these women compared to the general population, though lower than those with positive results.

The study analyzed almost 16,000 women in Ontario, Canada, who underwent BRCA testing between 2007 and 2016. Those who tested negative still had a 25% lifetime risk of breast cancer. Women with a variant of unknown significance faced a 30% risk, while the National Cancer Institute states the average risk for women is about 13%.

For those who test positive for BRCA1 or BRCA2, the risk rises to between 30% and 70%. The study, published in JAMA Network Open, found that family history significantly affects cancer risk. Positive BRCA mutation testers had a breast cancer risk between 56% and 86%, varying with family cancer history.

Dossa described the study’s data as an important basis for doctor-patient discussions on risk-reducing strategies such as high-risk screening, chemoprevention, and surgery, considering personal and family cancer history.

Currently, researchers are estimating cancer risk over time based on age-related development and the potential relationship between BRCA genes and heart health.

Kotryna Temcinaite from Breast Cancer Now emphasized the need to identify women at increased risk for early prevention or treatment. Despite family history being an important risk factor, most breast cancers aren’t linked to inherited gene changes. Regular self-exams, doctor visits for any changes, and attending screenings remain crucial. Lifestyle adjustments such as limiting alcohol, maintaining a healthy weight, and physical activity can also help reduce risk.

Reference: Dossa F, Metcalfe K, Ante Z, et al. Breast and Ovarian Cancer Among Individuals Undergoing BRCA1 and BRCA2 Testing. JAMA Netw Open. 2026;9(7):e2626334. doi:10.1001/jamanetworkopen.2026.26334