BRCA1 and BRCA2 are two genes that, when working normally, help repair DNA damage in cells; inherited mutations in either gene substantially increase the lifetime risk of breast and ovarian cancer and are the most common high-risk genetic cause of these cancers in the UK.
A BRCA mutation is a change in one of these two genes that interferes with their normal function. People who inherit a BRCA mutation have a significantly higher lifetime risk of breast and ovarian cancer than the general population. Knowing your BRCA status — through genetic testing — can change decisions about screening, chemoprevention, and (in some cases) risk-reducing surgery.
Orientation Why you might be reading about this
You may have a family history of breast or ovarian cancer and be considering genetic testing, or you may have already tested positive for a BRCA mutation and be working out what that means for the next decade of your life. Either way, the BRCA conversation is one of the more consequential in private breast practice. This page explains what BRCA is, what testing involves, and what the practical implications are.
Related terms: Mastectomy · Sentinel lymph node biopsy · Mammogram · DCIS · Risk-reducing mastectomy
Definition What BRCA1 and BRCA2 do
BRCA1 and BRCA2 are tumour suppressor genes — genes that, when functioning normally, help cells repair DNA damage and prevent uncontrolled cell division. Everyone has two copies of each gene (one inherited from each parent).
When a person inherits a mutation in BRCA1 or BRCA2 — a change in the gene that stops it working properly — the cells of the body have less effective DNA repair, and over time the chance of developing certain cancers rises. The mutations are inherited in an autosomal dominant pattern, which means that:
- A person who carries a BRCA mutation has a 50% chance of passing it to each child1.
- Both men and women can carry and pass on BRCA mutations.
Risk numbers What having a BRCA mutation means in numbers
The lifetime risk figures vary slightly between studies, but the patient-facing figures used in UK practice are approximately:
| Breast cancer risk by age 80 | Ovarian cancer risk by age 80 | |
|---|---|---|
| General population (UK) | ~12% | ~2% |
| BRCA1 carrier | ~72% (65–79%) | ~44% (36–53%) |
| BRCA2 carrier | ~69% (61–77%) | ~17% (11–25%) |
BRCA mutations also raise the lifetime risk of other cancers — particularly prostate cancer and pancreatic cancer in men with BRCA mutations — and a small additional risk of melanoma. The breast and ovarian risks are by far the largest.
Testing Testing for BRCA mutations
Genetic testing for BRCA is widely available on the NHS2 and privately, with an established pathway:
- Family-history risk assessment — usually with a clinical geneticist or family-history clinic. The risk is estimated using tools such as Tyrer-Cuzick or BOADICEA, taking into account who in the family has had breast or ovarian cancer, at what ages, and other factors.
- Genetic counselling — a structured conversation about what testing involves, what the possible results mean, and the implications for the patient and their relatives. Genetic testing is rarely done without counselling first.
- The test itself — a blood sample, sent for DNA analysis. Results take several weeks. Modern panels usually test for mutations in BRCA1, BRCA2, and several other related genes (PALB25, CHEK2, ATM, TP53) at the same time, because some of those have similar risk implications.
- Result and follow-up — a positive result triggers a discussion of surveillance, chemoprevention, and (if appropriate) risk-reducing surgery. A negative result in someone with a known family mutation is reassuring; a negative result where no family mutation has been identified is less informative.
Positive result What changes with a positive result
Knowing you carry a BRCA mutation does not automatically change the day-to-day; what it changes is the range of choices available to you over the years that follow:
Enhanced surveillance
For most BRCA carriers, annual breast MRI from age 30 (sometimes from 25) is recommended, often with annual mammography added from age 402. The aim is to detect any cancer that develops at the earliest possible stage. Surveillance does not prevent cancer; it catches it early.
Chemoprevention
Tamoxifen (typically for 5 years, in pre-menopausal patients4) and anastrozole or exemestane (in post-menopausal patients) reduce breast cancer incidence by around 30–50% in high-risk patients6. They have side effects — hot flushes, joint aches, a small thrombosis risk with tamoxifen — and the decision is individual.
Risk-reducing surgery
Bilateral risk-reducing mastectomy reduces breast cancer risk by approximately 90–95% in BRCA1 and BRCA2 carriers378. It is a major operation and a personal decision; surveillance and chemoprevention are reasonable alternatives. See risk-reducing mastectomy.
Risk-reducing salpingo-oophorectomy — removal of the fallopian tubes and ovaries — is recommended from age 35{nd}40 for BRCA1 carriers and age 40{nd}45 for BRCA2 carriers, once the patient has completed their family, performed by a gynaecological surgeon27. It reduces ovarian cancer risk substantially and also reduces breast cancer risk7.
Information for relatives
A positive BRCA result has implications for first-degree and second-degree relatives — parents, siblings, children, aunts and uncles. The clinical genetics team works with the patient on how to share the result and arrange testing for relatives who want it.
Negative result What changes with a negative result
A negative test in someone whose family has a known BRCA mutation is a true negative — the patient is not at the elevated risk associated with the mutation, and the family-history considerations no longer apply.
A negative test in someone whose family does not have an identified mutation is less definitive — there may still be a family-history risk that is not driven by a BRCA mutation, and surveillance may still be recommended on the basis of the family pattern even with a negative test.
At consultation What to discuss at consultation
For patients considering BRCA testing, conversations are usually with a clinical geneticist or a family-history clinic rather than a surgeon. For patients with a known BRCA result who are considering surgical risk reduction, the conversation moves to a surgical consultation, typically covering:
- The risk-reduction figures specific to your gene and your age.
- The alternatives — surveillance, chemoprevention — and how they compare to surgery.
- The operation itself: nipple-sparing or skin-sparing technique, reconstruction options, recovery, and outcomes.
- Timing — most patients consider this decision over months, not weeks.
For background, see risk-reducing mastectomy and contralateral risk-reducing mastectomy for patients with a previous breast cancer.
Resources Further reading
- NHS — Predictive genetic tests for cancer risk genes — UK patient overview of predictive genetic testing.
- NHS — Cancer overview — UK patient information including inherited risk.
- Breast Cancer Now — Genetic testing for altered breast cancer genes — patient-focused guide written by a UK breast cancer charity.
- Breastory: Risk-reducing mastectomy · Contralateral risk-reducing mastectomy · Non-cancerous breast conditions — family history section