BRCA1 and BRCA2 Gene Mutations
BRCA1 and BRCA2 are genes that help repair damaged DNA. When one of these genes carries a harmful change, that repair function is weakened, which significantly raises a person’s risk of developing certain cancers.
Key Takeaways
- BRCA1 and BRCA2 are tumor suppressor genes that normally help repair damaged DNA; a harmful change in either one weakens that repair function and raises cancer risk.
- The clearest risk increases are for breast and ovarian cancer, with smaller increases in pancreatic and prostate cancer risk; these changes are passed down in an autosomal dominant pattern.
- Genetic counseling and testing are generally reserved for people whose personal or family history meets specific criteria, not for the general population.
- A positive result does not predict whether or when cancer will occur, but it opens up options such as enhanced screening, risk-reducing surgery, and certain medications.
- A harmful BRCA change can also guide treatment choices once cancer develops, since some drugs work specifically against the DNA-repair defect it causes.
BRCA1 and BRCA2 Mutations Explained
BRCA1 and BRCA2 — the names stand for BReast CAncer gene 1 and BReast CAncer gene 2 — each code for a protein whose main job is fixing damaged DNA. Everyone has two copies of each gene, one inherited from each parent. Because their normal job is to help stop cells from growing and dividing in an uncontrolled way, they are classified as tumor suppressor genes.
Normal Function of BRCA Genes
The BRCA1 and BRCA2 proteins are best known for mending breaks in DNA, damage that happens routinely in cells from radiation, other environmental exposures, or simply as part of normal cell division. By fixing this damage, the two genes help keep a cell’s genetic material stable and functioning correctly.
How Mutations Occur
A BRCA1 or BRCA2 change can be inherited from a parent, in which case it is present from birth in essentially every cell of the body, or it can instead arise later, in just a specific cell, rather than being passed down at all. In most people who carry one inherited BRCA1 or BRCA2 change, the other, unaltered copy from the second parent still functions, and that single working copy is typically enough to keep a cell from becoming cancerous. Cancer becomes more likely if that remaining working copy is later damaged or lost within a particular cell, leaving it without enough working BRCA protein to repair its own DNA. A mutation therefore raises lifetime risk substantially without making cancer inevitable; some people who carry a harmful BRCA1 or BRCA2 change never develop cancer.
How BRCA Mutations Affect Cancer Risk
Carrying one of these BRCA1 or BRCA2 changes doesn’t cause cancer by itself, but it meaningfully raises the odds of several cancer types developing over a person’s lifetime. It also shifts the typical age of onset earlier: cancers linked to BRCA1 or BRCA2 tend to appear at a younger age than cancers in people who don’t carry such a change.
Associated Cancer Types
According to the National Cancer Institute, breast cancer carries the clearest elevated risk: a woman who carries a harmful BRCA1 or BRCA2 change has more than a 60% chance of developing breast cancer over her lifetime, versus roughly 13% for women without such a change. Ovarian cancer — which for this purpose includes cancer of the fallopian tube and primary peritoneum — follows a similar pattern: an estimated 39% to 58% lifetime risk for BRCA1 carriers and 13% to 29% for BRCA2 carriers, compared with about 1.1% among women generally. Men are not exempt either: by age 70, roughly 0.2% to 1.2% of men with a BRCA1 change and 1.8% to 7.1% of men with a BRCA2 change will develop breast cancer, versus about 0.1% of men overall.
Pancreatic and prostate cancer risk are higher too, according to the National Cancer Institute: lifetime pancreatic cancer risk reaches up to 5% for people with a BRCA1 change and 5% to 10% for those with a BRCA2 change, against about 1.7% in the general population. By age 80, prostate cancer affects an estimated 7% to 26% of men with a BRCA1 change and 19% to 61% of men with a BRCA2 change, compared with roughly 10.6% of men without one. Some research has also raised a possible link between BRCA changes and melanoma, stomach cancer, and a rare uterine cancer subtype, though that connection is not yet considered firmly established.
Inheritance Patterns and Family Risk
According to MedlinePlus Genetics, BRCA1 and BRCA2 mutations pass down in an autosomal dominant manner — inheriting just one changed copy from a mother or father is sufficient to elevate risk, and each offspring of a carrier has about a coin-flip (50%) odds of inheriting it too. Because the gene can come from either side of a family, a cluster of these cancers among relatives — on the mother’s or the father’s side — can point toward an inherited BRCA change, even though carrying the change itself produces no symptoms on its own.
How common a harmful change is also varies by ancestry, according to the National Cancer Institute: roughly 0.2% to 0.3% of people overall — about 1 in 400 — carry one of these harmful gene changes, but that share is higher in certain groups. About 2% of people with Ashkenazi Jewish ancestry carry one of three specific founder mutations, and similar founder mutations have been identified in several other populations, including Hispanic and West African ancestry, as well as Dutch, Icelandic, and Sephardi Jewish communities, among others.
Genetic Testing for BRCA1 and BRCA2
Genetic testing for BRCA1 and BRCA2 looks for a harmful change in either gene, typically using a small blood or saliva sample. A positive result means a person carries an increased risk of certain cancers; it cannot say whether or when cancer will actually develop.
Who Should Consider Testing
Testing isn’t recommended for everyone — it’s generally reserved for people whose personal or family history raises the likelihood of carrying a harmful BRCA1 or BRCA2 change. A referral for genetic counseling and testing is more likely when a relative is already known to carry a BRCA1 or BRCA2 change, when someone has Ashkenazi Jewish heritage, or when breast cancer was diagnosed — personally or in a close relative — at 50 or younger. A personal or blood-relative diagnosis of pancreatic cancer, ovarian cancer, breast cancer in a male relative, or metastatic/high-risk prostate cancer also raises the likelihood that testing will be recommended. Testing is generally not offered to children under 18, since there’s no BRCA-specific risk-reduction step for that age group.
The Testing Process
The lab work itself is straightforward — a blood or saliva sample analyzed for known BRCA1 and BRCA2 changes — but the counseling on either side of it matters just as much: reviewing personal and family history beforehand, and interpreting what a positive, negative, or uncertain result actually means afterward. A genetic counselor walks through those steps as part of the fuller testing process for hereditary cancer risk.
Managing Risk with BRCA Gene Mutations
For someone who tests positive for a harmful BRCA1 or BRCA2 change, managing that risk is typically an ongoing combination of closer screening, and a conversation about risk-reducing surgery or medication.
Proactive Screening and Prevention Strategies
Women with a harmful BRCA1 or BRCA2 change are generally advised to begin breast cancer screening earlier than average and to add breast MRI alongside annual mammography. Ovarian cancer has no reliable screening test: transvaginal ultrasound and CA-125 blood testing were used in the past, but research hasn’t shown that either one catches tumors soon enough to change long-term outcomes. Men who carry a harmful BRCA change should discuss breast and prostate cancer screening with their provider, and some guidelines call for pancreatic cancer screening in carriers who also have a close relative with pancreatic cancer.
Risk-reducing surgery removes the tissue most likely to turn cancerous. Two procedures come up most often: removing both breasts before cancer develops (bilateral risk-reducing mastectomy) to lower breast cancer risk, and removing the ovaries along with the fallopian tubes (a bilateral risk-reducing salpingo-oophorectomy) to lower ovarian cancer risk — a step that, particularly before menopause, may also lower breast cancer risk. Neither operation is reversible, neither removes all risk, and each carries its own possible complications. Tamoxifen and raloxifene are FDA-approved to lower breast cancer risk in women at elevated risk generally, though how well they work specifically for women with an inherited BRCA change isn’t yet fully clear. Oral contraceptive use has been linked to roughly half the ovarian cancer risk of never using one, in both BRCA carriers and the general population, though it may modestly raise breast cancer risk.
Treatment Approaches for Associated Cancers
A harmful BRCA1 or BRCA2 change can also shape how a resulting cancer gets treated. Because the mutated gene leaves cells less able to repair certain DNA damage, drugs called PARP inhibitors — including olaparib, rucaparib, niraparib, and talazoparib — are FDA-approved for several BRCA-related cancers, working by blocking a backup DNA-repair pathway the cancer cell still depends on. Platinum-based chemotherapy drugs, such as cisplatin, can be similarly effective against BRCA-related tumors for the same underlying reason. Breast cancers linked to a BRCA1 change are also more likely to be triple-negative, meaning they lack the receptors some targeted therapies rely on, which can make them harder to treat. Surgery and radiation remain part of the plan as well, individualized by cancer type, stage, and the specific gene involved.
Frequently Asked Questions
What does a positive BRCA test result mean for me?
It means a harmful change was found in BRCA1 or BRCA2 and that your lifetime risk of certain cancers, especially breast and ovarian cancer, is well above average. It does not mean you will definitely develop cancer, and it can’t say when or if that might happen. Most people use a positive result to plan closer screening and to discuss risk-reducing surgery or medication with their care team.
Can men also carry BRCA mutations and develop cancer?
Yes. Men can carry and pass on BRCA1 and BRCA2 changes just as women can. A harmful change raises a man’s risk of breast cancer (more so with BRCA2), prostate cancer, and possibly pancreatic cancer, though each of these risks is smaller in men than the comparable risks are in women. Genetic counseling and tailored screening are recommended for male carriers.
Are there lifestyle changes that can reduce cancer risk for BRCA carriers?
Lifestyle changes can’t offset the risk that comes from an inherited BRCA change, but general cancer-prevention habits — maintaining a healthy weight, staying physically active, limiting alcohol, and not smoking — are still worthwhile alongside medical management. For BRCA carriers specifically, enhanced screening and, where appropriate, risk-reducing surgery or medication are what most directly lower cancer risk.
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