Breast cancer is the commonest cancer affecting women. A family history of breast cancer increases a woman’s lifetime risk of developing the disease.
Most of the genetic risk is due to low-risk and moderate-risk susceptibility alleles rather than high-penetrance genes such as BRCA1 and BRCA2.
Pathogenic variants in these two tumour suppressor genes only account for about 2% of all breast cancers.
Female carriers of the BRCA gene pathogenic variants have a high lifetime risk of developing breast and ovarian cancer and male carriers have an increased risk of prostate and breast cancer.
Patients with a significant family history of breast cancer should be referred to their local cancer genetics service for a formal cancer genetics risk assessment, discussion of risk management options such as surveillance and risk-reducing surgery and consideration of genetic testing.
If a BRCA pathogenic variant is identified in a family, predictive testing can be offered to unaffected family members to clarify risks and help with risk management decisions.
Patients with cancer are increasingly likely to have tailored treatment,based on genetic information.
Targeted therapies exploiting vulnerabilities associated with deficient BRCA function are being developed.