Can a BRCA gene mutation cause triple-negative breast cancer?

BRCA genes are involved in repairing damaged DNA. When a harmful inherited variant interferes with repair, additional changes can accumulate in breast cells. Many carriers do not develop this cancer, and many people diagnosed with it have no inherited BRCA variant.

Triple-negative describes a tumour whose tested cells lack oestrogen receptors, progesterone receptors and excess HER2. It is a pathology classification, not a description of how advanced the cancer is and not proof that the cancer was inherited.

Genetic testing examines an inherited or acquired DNA change, while receptor testing examines features of the tumour. The results answer different questions and may each contribute to the treatment plan.

If you have been diagnosed, ask whether germline genetic testing is appropriate and whether tumour testing is also needed. Bring any earlier family genetic report, because testing for a known familial variant can be more focused.

If a pathogenic variant is confirmed, an oncology and genetics team can explain whether it affects surgical planning, medicine choices, future risk management or testing for blood relatives. A variant of uncertain significance should not be treated as a confirmed harmful mutation.

Arrange a clinical breast assessment for a new breast or underarm lump, skin dimpling, nipple inversion, bloody nipple discharge, or a persistent change in breast shape or skin. Such changes can have benign explanations, but examination should not be delayed because of age or genetic status.

During cancer treatment, contact the oncology team promptly for fever, breathlessness, uncontrolled vomiting, severe weakness or a rapidly worsening treatment reaction. Follow the team's emergency instructions if symptoms occur outside clinic hours.

Ask whether testing was performed on blood, saliva or tumour tissue; what the classification means; whether the finding changes treatment; and which relatives could benefit from a genetics referral.