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 — 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 — 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 $250–500 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 — 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 — 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 — 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 — 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
დაკავშირებული სახელმძღვანელოში (5)
- — The same population is at higher BRCA risk; ancestry-based screening and BRCA testing often go together.
- — A positive result means earlier, more intensive breast screening — and options well beyond it.
- — BRCA is the headline example — a clinical result that, for a carrier, can cut all-cause death with preventive surgery.
- — Carriers who choose risk-reducing ovary removal land in surgical menopause early. Plan the hormone-therapy conversation before, not after.
- — BRCA2 carriers face higher, earlier prostate-cancer risk — a reason to start this conversation sooner and weigh it differently.
BRCA1/2 Genetic Testing
Among the largest mortality effects in cancer prevention. In confirmed BRCA1/2 carriers, risk-reducing salpingo-oophorectomy is associated with HR 0.40 for all-cause mortality and HR 0.21 for ovarian-cancer-specific mortality (Domchek 2010, PROSE cohort n=2,482), and a 77% reduction in all-cause mortality to age 70 (Finch 2014, n=5,783). Risk-reducing mastectomy reduces breast cancer incidence by >90% (Hartmann 1999; Domchek 2010). Adjuvant olaparib in BRCA-mutated early breast cancer improves 3-year iDFS from 77.1% to 85.9% (Tutt 2021, OlympiA). The cascade-testing multiplier extends this to first-degree relatives at 50/50 prior probability.
The test is one blood draw or saliva sample plus one pre-test and one post-test counselling session — under two hours of clinic time. For the majority who test negative or carry no variant, effort ends there. Confirmed carriers do absorb a sustained surveillance routine (twice-yearly imaging) and a one-time surgical decision, but the test itself — the substance being scored — is a trivial single setup.
Penetrance estimates are settled across multiple large prospective cohorts (Kuchenbaecker 2017 n=9,856; Antoniou 2003 pooled n>8,000; King 2003 Ashkenazi). Risk-reducing surgery outcomes are documented in international prospective cohorts (Domchek 2010, Finch 2014, Hartmann 1999). PARP inhibitor benefit is RCT-grade and FDA-approved (Robson 2017 OlympiAD, Tutt 2021 OlympiA). USPSTF 2019 Grade B; NCCN guideline-anchored; ACMG/NSGC consensus on counselling pathway.
The test itself is $250–500 cash through commercial labs (Invitae, Ambry, Color) and routinely covered by US insurance and the UK NHS when NCCN/USPSTF criteria are met. Downstream costs for confirmed carriers are larger but spread over decades: annual breast MRI plus mammogram is in the low thousands per year before insurance, and risk-reducing surgery is a five-figure procedure largely reimbursed when indicated. Net out-of-pocket for a typical pathway lands in the minor range for most patients.
Real but mixed-direction effect on inner wellbeing. A true negative against a known familial variant produces meaningful, durable psychological relief and removes a multi-decade source of family dread. A confirmed-positive result carries non-trivial distress in the months around disclosure, though most cohorts find this normalises within a year. Cascade testing reduces ambient uncertainty across the family. Not the reason to do the test, but a genuine secondary consequence of moving from unknown to known.