BRCA1 and BRCA2 are DNA repair genes. You inherit two copies; a pathogenic variant means one is broken from birth, in every cell. The cell copes on the working copy โ until, over decades in breast or ovarian tissue, that one breaks too, repair fails, and a tumour starts. The same broken-repair logic makes these tumours unusually vulnerable to PARP-inhibitor drugs 1, so the result changes both prevention and treatment.
The numbers are large, and the mortality data is real. A BRCA1 carrier has roughly 72% lifetime breast and 44% ovarian cancer risk; BRCA2, 69% and 17% 2. Baseline is about 13% and 1.3%. Removing the ovaries and tubes before menopause cut death before 70 by roughly three-quarters 3; risk-reducing mastectomy cut later breast cancer by over 90% 4.
Most people shouldn't test. Carriers are about 1 in 400. Talk to a genetic counsellor if any of these hit you or a close blood relative:
- Breast cancer at or before 50, or triple-negative at any age
- Ovarian, fallopian-tube, or peritoneal cancer at any age
- Male breast cancer, metastatic prostate, or pancreatic cancer
- Two close relatives on the same side with any of the above
- A known BRCA variant in the family, or Ashkenazi Jewish ancestry with any family cancer history
If a first-degree relative has a known variant, your prior is 50% and your test is a single cheap check โ the most cost-effective cancer prevention there is 5.
The pathway is almost entirely paperwork.
The lab runs a full panel, so PALB2, CHEK2, ATM and others come along free 6. A US panel runs $250โ500 cash, usually covered when you qualify; the UK NHS tests free on indication.
What a result actually does. Most takers get the negative they wanted: within a month the family "what if" gets archived, for them and their kids. Come back positive, and the next decades reshape โ MRI and mammogram alternating every six months, and ovary-and-tube removal between 35 and 45 once childbearing is done 7. The trade is surgical menopause now for a life expectancy climbing back toward baseline 8. Each first-degree relative then gets a single-variant check resolved in a week.
The fine print โ when to skip it, and what people get wrong
- "No family history, so not me." Up to half of carriers miss family-history-only criteria; fathers transmit at the same rate as mothers 5.
- "My 23andMe was clear." It reads three Ashkenazi founder variants only; outside that ancestry it misses over 99.9% of pathogenic findings 9.
- "It's a women's test." BRCA2 men carry ~7% breast and ~20% aggressive-prostate lifetime risk 6.
- Don't test minors for adult-onset risk; wait until they can consent and act.
- Don't skip pre-test counselling โ a positive with no plan drives decisions made in panic.
- Insurance gap: US law bars health and job discrimination, but not life or disability cover; buy those before testing if you plan to.
- 1Robson et al. (2017). Olaparib for Metastatic Breast Cancer in Patients with a Germline BRCA Mutation. New England Journal of Medicine. link
- 2Kuchenbaecker et al. (2017). Risks of Breast, Ovarian, and Contralateral Breast Cancer for BRCA1 and BRCA2 Mutation Carriers. JAMA. link
- 3Finch et al. (2014). Impact of Oophorectomy on Cancer Incidence and Mortality in Women With a BRCA1 or BRCA2 Mutation. Journal of Clinical Oncology. link
- 4Hartmann et al. (1999). Efficacy of Bilateral Prophylactic Mastectomy in Women with a Family History of Breast Cancer. New England Journal of Medicine. link
- 5Manchanda et al. (2015). Population Testing for Cancer Predisposing BRCA1/BRCA2 Mutations in the Ashkenazi-Jewish Community: A Randomized Controlled Trial. Journal of the National Cancer Institute. link
- 6NCCN (2024). NCCN Clinical Practice Guidelines in Oncology: Genetic/Familial High-Risk Assessment โ Breast, Ovarian, and Pancreatic, Version 3.2024. link
- 7Saslow et al. (2007). American Cancer Society Guidelines for Breast Screening with MRI as an Adjunct to Mammography. CA: A Cancer Journal for Clinicians. link
- 8Domchek et al. (2010). Association of Risk-Reducing Surgery in BRCA1 or BRCA2 Mutation Carriers With Cancer Risk and Mortality. JAMA. link
- 9FDA (2018). FDA Authorizes, with Special Controls, Direct-to-Consumer Test that Reports Three Mutations in the BRCA Breast Cancer Genes. link
Related in the handbook (5)
- โ The same population is at higher BRCA risk; ancestry-based screening and BRCA testing often go together.
- โ A positive result means earlier, more intensive breast screening โ and options well beyond it.
- โ BRCA is the headline example โ a clinical result that, for a carrier, can cut all-cause death with preventive surgery.
- โ Carriers who choose risk-reducing ovary removal land in surgical menopause early. Plan the hormone-therapy conversation before, not after.
- โ BRCA2 carriers face higher, earlier prostate-cancer risk โ a reason to start this conversation sooner and weigh it differently.
BRCA1/2 Genetic Testing
One of the biggest mortality reductions in cancer prevention โ if you carry a BRCA variant and act on it, all-cause mortality before age 70 drops by roughly three-quarters.
One blood or saliva sample plus two short counselling visits. The work is mostly in the decision before testing, not the test itself.
Settled science: penetrance numbers from cohorts of thousands, surgery outcomes tracked for decades, targeted drugs approved on RCT evidence.
The test runs $250โ500 out of pocket and is routinely covered when you meet criteria. Surveillance and surgery costs come later and only if positive.
Knowing replaces dread. A clean result lifts a multi-decade family worry; a positive result trades uncertainty for a plan.