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 surveil-
lance 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 vulnerabil-
ities associated with deficient
BRCA
function are being developed.