BRCA1 and BRCA2: What Your Genetic Risk for Breast and Ovarian Cancer Really Means

BRCA1 and BRCA2: What Your Genetic Risk for Breast and Ovarian Cancer Really Means

This article is for educational purposes only. It is not a substitute for professional medical advice. Always consult a licensed physician, medical geneticist, or genetic counselor. Do this before any decision about testing, treatment, or ongoing care. In a medical emergency, call 911.

Bottom line: A large pooled analysis studied BRCA1/BRCA2 carriers. It found that their lifetime cancer risk is far above average. But this same research shows risk is not identical for everyone. A newer trial has also changed how BRCA-related cancer gets treated.

What you’ll learn:

• What BRCA1 and BRCA2 actually do, and why a mutation runs in families
• What your real, numeric risk looks like — not just “higher than average”
• The difference between a clinical genetic test and a consumer kit like 23andMe
• What your options are if you test positive: screening, surgery, and new drugs

How BRCA1 and BRCA2 Work — and Why This Runs in Families

BRCA1 and BRCA2 are not “cancer genes” in the sense of causing cancer directly. They are tumor-suppressor genes instead. Their normal job is to help repair a specific kind of DNA damage. This damage is called a double-strand break. Repair must happen before a damaged cell can divide and multiply.

Think of them as a repair crew. Every day, small cracks form in the wall of your DNA. Most get patched quietly, before anyone notices. BRCA1 and BRCA2 are two of the main tools in that repair crew’s kit.

Everyone has two copies of BRCA1 and two copies of BRCA2. One copy of each gene comes from each parent. A person “carries a BRCA mutation” only when one copy has a pathogenic variant. Pathogenic means disease-causing. The other copy still works.

That is why carriers are not born with cancer. Most carriers spend decades in good health.

Over a lifetime, though, a single cell can lose its one remaining working copy. This happens through further DNA damage. Once that happens, DNA repair breaks down inside that cell. Damaged cells that should have died instead survive and multiply. Cancer risk then rises sharply in certain tissues. Breast and ovary are the tissues most affected, along with a few others.

This inheritance pattern is called autosomal dominant. That means a single altered copy from either parent is enough to raise risk. You do not need two copies.

Each child of a carrier has about a 50 out of 100 chance of inheriting it. This is true for both sons and daughters. It works like a coin flip repeated separately for every child. A parent’s sex does not change these odds.

A child’s sex does not change whether the gene passes down. It does change which cancers become more likely once the gene is inherited. Male carriers face a modestly elevated risk of breast and prostate cancer. Female carriers face a different pattern, which includes ovarian cancer risk.

It also helps to know what BRCA1/BRCA2 mutations are not. They are not contagious. They do not “skip a generation” in any predictable pattern. The 50-50 odds apply fresh to each child.

Having the mutation does not mean every relative will test positive. Some relatives will carry it; some will not, purely by chance. If this feels overwhelming for your family, a genetic counselor can help. A counselor can walk through it with you, step by step.

Section recap: BRCA1 and BRCA2 normally repair DNA damage. A mutation weakens that repair system in one copy. The mutation passes down with roughly 50-50 odds to each child. This is true regardless of the child’s sex.

How Much Does a BRCA Mutation Actually Raise Your Risk?

This is the question most people actually want answered. Vague phrases like “significantly increased risk” do not answer it. A large pooled analysis of cohort studies gives real numbers instead:

• Breast cancer by age 80: about 72 of 100 BRCA1 carriers develop it. About 69 out of 100 BRCA2 carriers do. Compare that with roughly 13 out of 100 women in the general population. This is a lifetime-risk figure, not a per-year risk.
• Ovarian cancer by age 80: about 44 of 100 BRCA1 carriers develop it. About 17 out of 100 BRCA2 carriers do. Compare that with roughly 1 to 2 out of 100 in the general population. This is also a lifetime-risk figure.
• Second breast cancer within 20 years: this means after a first diagnosis. About 40 out of 100 BRCA1 carriers face this. About 26 out of 100 BRCA2 carriers do.

Two things stand out in these numbers. First, BRCA1 and BRCA2 do not carry identical risk profiles. BRCA1 carries a notably higher ovarian cancer risk than BRCA2. Their breast cancer risk, though, is fairly close.

Second, “72 out of 100 by age 80” sounds high. But that also means 28 of 100 BRCA1 carriers will not get it by that age. A positive result raises the odds substantially. It does not decide the outcome by itself.

There is also a timing pattern worth knowing. BRCA-related cancers tend to appear earlier in life than average. Breast cancer, for example, often shows up before age 50. Carrier screening starts years earlier than general guidelines recommend.

These population-level numbers do not automatically describe your own risk. Several things can shift an individual estimate from the published range. One is family history density. This means how many close relatives were affected, and at what age.

Another is the exact variant involved. This is one reason guidelines direct carriers toward personalized counseling. A single number from a study cannot capture everything. A genetic counselor can walk through your specific family tree. A counselor can translate a population average into an individualized picture.

Section recap: BRCA1’s breast cancer risk is a bit higher than BRCA2’s. BRCA1 also carries notably higher ovarian cancer risk. Both are well above the general population. Neither is 100 out of 100.

Getting Tested: Clinical Testing vs. DNA Kits Like 23andMe

There are two very different paths to a BRCA result in the US and Canada. Confusing them can be dangerous.

Clinical, insurance-eligible testing is ordered by a doctor or counselor. This usually follows a structured risk assessment. The USPSTF (US Preventive Services Task Force) recommends this in two cases. One: personal or family history of breast, ovarian, tubal, or peritoneal cancer. The other is ancestry linked to higher BRCA prevalence.

The USPSTF also recommends genetic counseling both before and after testing. This is not only after a result comes back. This route typically sequences the full BRCA1 and BRCA2 genes. It can detect most known pathogenic variants, not just a handful.

Direct-to-consumer (DTC) kits work very differently. This is where confusion causes real harm. The best-known example is 23andMe’s report. It is FDA-authorized, formally the BRCA1/BRCA2 (Selected Variants) report.

It checks only 3 specific variants. Those 3 variants are most common in people of Ashkenazi Jewish ancestry. The report does not scan the rest of either gene.

A negative result here does not rule out other pathogenic BRCA variants. Thousands of other pathogenic BRCA variants exist worldwide. It only rules out those 3 specific ones. The FDA itself has warned that this distinction is easy to miss. The FDA has said the report “does not describe a person’s overall risk.”

Path	What it checks	Best for
Clinical diagnostic test (physician/counselor-ordered)	Full BRCA1 + BRCA2 sequencing, often bundled with a broader cancer gene panel	Anyone with a concerning personal or family history
23andMe Health Predisposition report	3 specific Ashkenazi-founder variants only	Screening within that ancestry group — not a general clearance
Other clinical-grade options (e.g., Color, Invitae)	Broader multigene panels, typically ordered alongside counseling	People wanting more comprehensive testing outside a traditional clinic visit

A genetic counselor can help you decide which testing path fits your history. You can search for one at NSGC.org. A counselor can order confirmatory testing if a DTC result raises questions. This applies even after a negative DTC screen, if family history is concerning.

Section recap: A negative DTC screen is not a negative full clinical test. Ask a provider or counselor about full sequencing if history is concerning.

What Your Result Actually Means: Positive, Negative, and “Uncertain”

Genetic test reports generally fall into three categories. Only one of them gives a clear, actionable answer on its own.

• Pathogenic/likely pathogenic: known or suspected disease-causing variant. This is what “testing positive” usually means in everyday conversation. It is the result that typically changes screening and prevention plans.
• Benign or likely benign: no meaningfully higher risk from this variant. This is the most common outcome for people without a strong family history.
• Variant of uncertain significance (VUS): a change in the gene was found. Current scientific evidence is not enough to call it harmful or harmless. This is more common than people expect, especially with broader gene panels.

Guidelines caution against making major medical decisions based on a VUS alone. Surgery, in particular, should not be based on a VUS alone. Most VUS findings are eventually reclassified as benign. This happens once more research data accumulates over time. A result that looks alarming today may be relabeled “benign” in a few years. This happens once enough other people with the same variant have been studied.

A newer trend adds a fourth wrinkle to this picture: broader multigene panels. The 2024 ASCO (American Society of Clinical Oncology) update expands testing. This goes beyond BRCA1/2 alone. It adds genes like PALB2, CHEK2, and ATM to the standard panel. This especially applies at a new breast cancer diagnosis. A result can now affect treatment choice directly, not just prevention.

The tradeoff is that broader panels also turn up more VUS findings. This happens simply because more genetic territory is being scanned. That is exactly why pretest counseling matters. A patient should know what an uncertain result does, and doesn’t, mean.

Section recap: Only pathogenic/likely-pathogenic results change care. A VUS is neither “yes” nor “no.” Ask a counselor to help interpret it.

Lowering Your Risk: Screening, Surgery, and Prevention Options

A positive result is not only bad news. It is also a set of concrete, guideline-based options. People without a mutation do not get these options this early in life.

NCCN (National Comprehensive Cancer Network) sets a pathway for carriers:

• Enhanced screening: annual breast MRI starts around age 25-29. Annual mammography is added from age 30. This is roughly twice as often as the general-population schedule. Screening also starts much earlier.
• Risk-reducing salpingo-oophorectomy: surgery to remove ovaries and tubes. Typically recommended at ages 35-40 for BRCA1 carriers, and 40-45 for BRCA2. This is usually timed for once childbearing is complete. It is the single option shown to meaningfully cut ovarian cancer risk. No screening test is as effective as removal for this particular cancer.
• Risk-reducing mastectomy: a personal choice, not a required step. Discuss it with a surgeon and genetic counselor. Guidelines present it as optional, not required. Many carriers choose enhanced screening instead, at least for some years.
• Chemoprevention (such as tamoxifen): discussed with your oncologist. The goal is lowering breast cancer risk without surgery.

None of these is a one-size-fits-all recommendation. None should be chosen in isolation. A genetic counselor or breast/ovarian cancer specialist weighs several factors. These include age, family history, the gene involved, and personal preference.

This weighing happens before recommending any particular combination. Skipping that conversation is risky. Choosing a path alone from an internet search is risky, too. These detailed guidelines exist to prevent exactly that.

Cost and access matter here too. Guideline-concordant screening and surgery are usually insurance-eligible. This applies in both the US and Canada, for a confirmed pathogenic variant. Prior authorization and coverage still vary by plan and province, though. A genetic counselor’s office can often help navigate this process, too.

Section recap: Enhanced screening starts years earlier than average. Risk-reducing surgery timing differs by gene, too. BRCA1 carriers are usually counseled toward earlier surgery than BRCA2 carriers.

New Treatments: How a BRCA Mutation Now Changes Cancer Treatment Itself

Until recently, a BRCA result mainly shaped prevention and screening choices. That has changed in the last few years.

The OlympiA trial was a large randomized controlled study. It tested olaparib, a PARP-inhibitor drug, as an add-on to chemotherapy. The trial enrolled patients with early-stage, HER2-negative breast cancer. These patients also carried a germline BRCA1 or BRCA2 mutation.

Three years later, 86 of 100 olaparib patients were free of invasive disease. In the placebo group, that number was about 77 out of 100. A 9-point gap is meaningful at this stage of cancer treatment.

Based on those results, two regulators acted. The FDA approved olaparib (Lynparza) for this adjuvant use on March 11, 2022. Health Canada authorized a corresponding indication that same year. This is a genuinely new development.

It made germline BRCA status directly relevant to treatment choice at diagnosis. Before, BRCA status was only relevant to future risk assessment, decades later. This is why 2024 ASCO guidance recommends considering testing at diagnosis. Before, testing was only offered afterward for prevention planning.

Like any therapy, olaparib has its own side effects and eligibility criteria. An oncologist decides eligibility based on the full clinical picture. This includes tumor traits, prior treatment, and health, not BRCA status alone.

The takeaway for a general reader is narrower and more concrete. A BRCA result found today can open a specific, evidence-backed treatment door. That door simply did not exist a decade ago.

Section recap: Since March 2022, olaparib is FDA-approved for carriers. A germline mutation can qualify a patient for it after chemotherapy. This is not just about extra screening or prevention anymore.

What a BRCA Result Means for Your Family

A pathogenic BRCA variant is a family finding, not only a personal one. Once one relative tests positive, their first-degree relatives are affected too. Parents, siblings, and children each face a 50 out of 100 chance. This is why genetic counselors routinely discuss cascade testing.

Cascade testing offers testing to close relatives once a variant is found. Cascade testing lets relatives learn their own status before cancer develops. This is better than waiting until a diagnosis forces the question.

Public health experts see real value in this beyond any one family. The CDC (Centers for Disease Control and Prevention) tracks this closely. It calls this a “Tier 1” genomic application, its strongest evidence tier. Yet the CDC notes most carriers of a pathogenic BRCA1/2 variant do not know it.

A big reason: family-history isn’t consistently asked about at checkups. That gap is exactly what cascade testing is meant to close. Simply asking about family cancer history at checkups helps too.

Cascade testing itself is voluntary and deeply personal. Some relatives want to know as soon as possible. Others prefer to wait. Some choose never to test. That choice deserves respect too. A genetic counselor can help a carrier decide how, when, and whom to tell.

This can include practical scripts for difficult conversations. No relative should be pressured into a decision they are not ready to make.

Section recap: A positive result is info close relatives may want, too. Cascade testing lets them learn their own risk early, on their own timeline. Most carriers nationally still don’t know their status.

Insurance, Work, and Telling Your Family: The Emotional Side

Two practical fears keep many people from testing at all. One fear is losing insurance coverage; the other is losing a job. Both deserve straight answers.

In the US, GINA (Genetic Information Nondiscrimination Act) answers part of it. GINA’s Title I covers health insurance. It bars insurers from using genetics for eligibility, coverage, or premiums. That includes both a BRCA test result and your family history.

GINA’s Title II covers employers with 15+ employees. It bars them from using genetic information in hiring, firing, or promotion.

Importantly, GINA excludes life, disability, and long-term-care insurance. That is a real, legally permitted gap. Discuss this with a genetic counselor or financial advisor before testing. This matters especially if you are shopping for one of those policies soon.

Canada’s protection is broader. Its Genetic Non-Discrimination Act has been law since 2017. The Supreme Court of Canada upheld its constitutionality in a 2020 ruling. The law bars genetic testing as a contract condition. It also bars requiring disclosure of test results as a contract condition. This includes insurance contracts of any kind.

That closes a gap that still exists south of the border in the US.

Beyond legal protection, there is the harder question of family disclosure. What do you tell a partner? Your children, once they are old enough to understand? Siblings who may not want to know? There is no single right answer to any of these questions. No guideline can fully settle it for you.

A counselor’s job includes helping carriers work through this at their pace. Support groups such as FORCE connect carriers with others who’ve faced this. FORCE stands for Facing Our Risk of Cancer Empowered. Many people find that easier than working through it alone.

Section recap: US and Canadian legal protections differ meaningfully. GINA has real gaps in life/disability insurance Canada’s law doesn’t share. A genetic counselor can help plan disclosure to both family and employers.

Frequently Asked Questions

Q1. If I test positive for a BRCA mutation, will I definitely get cancer?

No. Lifetime risk is well above average. It runs up to about 72 out of 100 for BRCA1-related breast cancer by age 80. But a meaningful share of carriers never develop the disease at all. It is a strong risk factor. It is not a certainty.

Q2. My mother just tested positive. Should I get tested too?

Talk to a board-certified genetic counselor first. Don’t test on your own through a DTC kit. As a first-degree relative, you have about a 50-in-100 chance of carrying it. Cascade testing lets you find out on a planned, supported timeline. Someone will be available to help you interpret the result.

Q3. Does 23andMe test for all BRCA mutations?

No. The FDA-authorized 23andMe report checks only 3 specific variants. These are common mainly in Ashkenazi Jewish ancestry. A negative result doesn’t rule out other pathogenic variants worldwide.

Q4. Will a positive BRCA result affect my health insurance or my job?

In the US, GINA protects health insurance and most employment decisions. It explicitly excludes life, disability, or long-term-care insurance. In Canada, the law covers insurance contracts more broadly, no carve-out.

Q5. Is there a new treatment if I already have BRCA-related breast cancer?

Yes, for some patients. Since March 2022, adjuvant olaparib is an option for eligible patients. It is specifically for early-stage, HER2-negative, BRCA-mutated cancer. This is based on the OlympiA trial. Ask your oncologist whether your specific case qualifies.

The Takeaway

A BRCA1/BRCA2 mutation raises breast/ovarian cancer risk well above average. The numbers from large pooled studies make that clear, not vague. But “well above average” is not “certain.” This research also defines a growing set of responses to that risk.

That includes earlier and more frequent screening. It includes surgical timing that differs by gene. Since 2022, it includes an FDA-approved drug, too. That drug is for BRCA-mutated early breast cancer.

Most carriers in the general population still do not know their status. A big reason: family-history screening isn’t asked about consistently. If your family history includes early breast or ovarian cancer, close that gap.

You may wonder whether to test, how to read a result, or what to tell family. You do not have to work any of it out alone. A board-certified genetic counselor is one reliable starting point. You can search for one at NSGC.org. Your primary care provider or oncologist is another good starting point. They can turn these population-level numbers into a plan that fits your history.

This article is for educational purposes only. It is not a substitute for a physician, medical geneticist, or counselor. Decisions about testing, disclosure, and treatment need a qualified clinician. In emergencies, call 911 (US/Canada) or 119 (Japan).

References

1. Kuchenbaecker KB, et al. (2017) Risks of Breast, Ovarian, and Contralateral Breast Cancer for BRCA1 and BRCA2 Mutation Carriers. JAMA. https://jamanetwork.com/journals/jama/fullarticle/2632503
2. Tutt ANJ, et al. (2021) Adjuvant Olaparib for Patients with BRCA1- or BRCA2-Mutated Breast Cancer (OlympiA). New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa2105215
3. FDA. Approval of olaparib (Lynparza) for adjuvant treatment of BRCA-mutated, HER2-negative high-risk early breast cancer, March 2022. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-olaparib-adjuvant-treatment-high-risk-early-breast-cancer
4. National Cancer Institute (NIH). BRCA Gene Mutations: Cancer Risk and Genetic Testing. https://www.cancer.gov/about-cancer/causes-prevention/genetics/brca-fact-sheet
5. NCCN Clinical Practice Guidelines in Oncology: Genetic/Familial High-Risk Assessment — Breast, Ovarian, and Pancreatic. https://www.nccn.org/guidelines/guidelines-detail?category=2&id=1503
6. US Preventive Services Task Force (2019). Risk Assessment, Genetic Counseling, and Genetic Testing for BRCA-Related Cancer. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/brca-related-cancer-risk-assessment-genetic-counseling-and-genetic-testing
7. ACMG / NSGC. Practice guideline on genetic counseling and testing for hereditary breast and ovarian cancer. https://www.nsgc.org/POLICY/Position-Statements
8. US EEOC. Genetic Information Nondiscrimination Act (GINA) of 2008. https://www.eeoc.gov/genetic-information-discrimination
9. Government of Canada. Genetic Non-Discrimination Act (2017). https://laws-lois.justice.gc.ca/eng/acts/g-2.5/
10. FDA. Authorization of the 23andMe BRCA1/BRCA2 (Selected Variants) Health Predisposition report, 2018. https://www.fda.gov/news-events/press-announcements/fda-authorizes-first-direct-consumer-test-detecting-genetic-variants-may-be-associated-increased
11. American Society of Clinical Oncology (ASCO) (2024 update). Germline and Somatic Genetic Testing for Cancer Susceptibility. https://ascopubs.org/doi/10.1200/JCO.24.00000
12. Centers for Disease Control and Prevention (CDC). Office of Genomics and Precision Public Health — Hereditary Breast and Ovarian Cancer. https://www.cdc.gov/genomics/disease/breast_ovarian_cancer/index.htm

Last updated: 2026-07-11

Author: Yu Mizuno (Editor-in-Chief, non-physician), GeneLumen editorial team. This article aggregates 12 peer-reviewed and public-health sources. Sources are tier-rated: tier 1=8, tier 2=4. They include NIH, CDC, Health Canada, FDA, ACMG/NSGC, and NCCN guidelines. PubMed-indexed publications are included too.

This article is for educational purposes only. It is not a substitute for advice from a physician, geneticist, or counselor. In emergencies, call 911 (US/Canada) or 119 (Japan).