Around 5–10% of all breast cancers are caused by inherited gene mutations. BRCA1 and BRCA2 are the most significant — and the most actionable. A woman who carries a BRCA1 mutation has a lifetime breast cancer risk of around 72% (versus 12% in the general population) and a substantially elevated risk of ovarian cancer. Identifying a mutation changes the clinical pathway significantly: it triggers enhanced surveillance, opens the door to risk-reducing surgery, and has implications for blood relatives who may also be carriers.
Who the NHS currently offers BRCA testing to
NICE guidelines (NG151) set out the criteria for NHS genetic testing for BRCA1 and BRCA2. Testing is offered through clinical genetics services when a person meets a risk threshold based on personal and family history. Key triggers include: a first-degree relative diagnosed with breast cancer under 40; two or more close relatives on the same side of the family with breast cancer; a close relative with triple-negative breast cancer; a history of male breast cancer in the family; or a combination of breast and ovarian cancer in close relatives.
How the test works
BRCA testing is a blood test. A sample is taken and analysed in a laboratory for variants in the BRCA1 and BRCA2 genes. Results typically take several weeks and are delivered with genetic counselling — a specialist who helps you understand the implications before and after testing. Pre-test counselling is important because a positive result affects not just you, but potentially your parents, siblings and children, who each have a 50% chance of carrying the same variant.
What a positive result means in practice
- Enhanced surveillance: annual MRI from age 30 (or 25 for BRCA1 carriers), in addition to mammography
- Risk-reducing medication: tamoxifen or aromatase inhibitors can reduce breast cancer risk in high-risk pre- and post-menopausal women
- Risk-reducing surgery: bilateral mastectomy reduces risk by around 90%; bilateral salpingo-oophorectomy reduces ovarian cancer risk and, if done before menopause, also reduces breast cancer risk
- Cascade testing: first-degree relatives should be offered testing; the NHS will typically facilitate this through the clinical genetics team
- Reproductive options: pre-implantation genetic diagnosis (PGD) is available through some NHS pathways for those who wish to avoid passing the variant to children
Testing after a breast cancer diagnosis
BRCA testing is increasingly offered as part of the diagnostic pathway for newly diagnosed breast cancer, particularly for: women diagnosed under 40; women with triple-negative breast cancer; women of Ashkenazi Jewish ancestry (where BRCA founder mutations are more common); and women with a significant family history. A positive result at diagnosis can influence surgical decisions — for example, whether to proceed with lumpectomy or bilateral mastectomy — and may affect choice of systemic treatment, as BRCA-mutated tumours are particularly sensitive to PARP inhibitors.
Other inherited breast cancer genes
BRCA1 and BRCA2 are the most clinically significant, but not the only breast cancer-associated genes. PALB2, CHEK2, ATM, and several others are associated with moderate increases in breast cancer risk. Multigene panel testing — testing multiple genes simultaneously — is increasingly offered in clinical genetics services, and the management implications for these moderate-risk genes are an active area of NHS clinical guidance development.