BRCA1 and BRCA2 are genes that every person has. Their job is to repair damaged DNA and suppress tumor growth. When either gene carries a harmful mutation, your body loses a critical layer of protection against cancer, particularly breast and ovarian cancer. More than 60% of women who inherit a harmful change in BRCA1 or BRCA2 will develop breast cancer during their lifetime.
What BRCA Genes Normally Do
Your DNA breaks constantly. Radiation, chemicals, and even normal cell division can snap both strands of the DNA double helix. These double-strand breaks are among the most dangerous types of DNA damage because they can lead to mutations that drive cancer growth. BRCA1 and BRCA2 are part of the repair crew that fixes them.
The repair process, called homologous recombination, works like this: when a break occurs, the BRCA proteins help load a repair molecule called RAD51 onto the damaged strand. RAD51 then searches for an intact copy of the same DNA sequence on the sister chromosome and uses it as a template to restore the broken section accurately. BRCA1 helps initiate this process by recruiting the other repair proteins to the break site. BRCA2’s main role is assembling and stabilizing the RAD51 filaments that carry out the actual repair. Without functional BRCA proteins, your cells fall back on sloppier repair methods that introduce errors, and those errors accumulate over time into the kind of mutations that can trigger cancer.
How BRCA Mutations Raise Cancer Risk
A harmful BRCA mutation doesn’t guarantee cancer, but it dramatically shifts the odds. In the general population, a woman’s lifetime risk of breast cancer is about 13%. For women with a BRCA1 or BRCA2 mutation, that number climbs above 60%.
Ovarian cancer risk is where the two genes diverge most sharply. Women with a BRCA1 mutation face a 39% to 58% lifetime risk of ovarian cancer (a category that includes fallopian tube and primary peritoneal cancers). For BRCA2 carriers, the range is 13% to 29%. Both are far above the roughly 1.2% lifetime risk in the general population.
Risks for Men
BRCA mutations are often discussed in the context of women’s health, but men carry these genes too and face their own elevated risks. Men with a BRCA2 mutation have a 5% to 10% lifetime risk of breast cancer, and those with BRCA1 mutations have a 1% to 5% risk. While those numbers sound small, male breast cancer in the general population is extremely rare, so even a few percentage points represents a significant increase.
Prostate cancer is the bigger concern. Men with either BRCA mutation face a 25% to 50% lifetime risk of prostate cancer, and BRCA-related prostate cancers tend to be more aggressive. Pancreatic cancer risk also rises: 2% to 3% for BRCA1 carriers and 3% to 5% for BRCA2 carriers, compared to about 1.7% in the general population.
How BRCA Mutations Are Inherited
BRCA mutations follow an autosomal dominant inheritance pattern, meaning you only need one copy of the mutated gene (from either parent) to have elevated cancer risk. If one of your parents carries a BRCA mutation, you have a 50% chance of inheriting it. This applies equally to sons and daughters.
Roughly 1 in 400 people in the general population carries a harmful BRCA mutation. Certain ethnic groups have significantly higher rates. Among people of Ashkenazi Jewish descent, the prevalence is roughly 1 in 40, about ten times the general population rate. In one study, 10% of Ashkenazi Jewish women diagnosed with breast cancer in their forties carried one of the known BRCA mutations.
Screening and Monitoring for Carriers
If you know you carry a BRCA mutation, screening typically starts earlier and is more intensive than standard guidelines. Most recommendations call for annual breast MRI beginning at age 25 to 30, with mammography added around age 30. The combination of MRI and mammography catches cancers that either test alone would miss, which matters because BRCA-related breast cancers often develop at younger ages when breast tissue is denser and harder to image.
For ovarian cancer, screening is less reliable. There is no equivalent of a mammogram for the ovaries. Transvaginal ultrasound and blood tests for the CA-125 marker are sometimes used, but they have not been shown to reliably catch ovarian cancer early enough to improve outcomes. This is one reason preventive surgery is discussed so often with carriers.
Risk Reduction Options
Preventive (prophylactic) bilateral mastectomy reduces breast cancer risk by at least 95% in women with a harmful BRCA mutation. It is the most effective risk-reduction option available, though it is clearly a major decision with lasting physical and emotional effects. Some women choose this path after completing childbearing; others prefer intensive screening instead. Neither choice is wrong.
Preventive removal of the ovaries and fallopian tubes (salpingo-oophorectomy) addresses ovarian cancer risk, which is particularly important because ovarian cancer is difficult to detect early. This surgery also appears to reduce the overall risk of dying from any cause after a breast cancer diagnosis by more than half for BRCA carriers. Some studies suggest it lowers breast cancer risk as well, though the evidence there is mixed. Because the surgery triggers immediate menopause, the timing involves trade-offs around bone health, heart health, and quality of life that vary by age.
Medications that block estrogen can also lower breast cancer risk for some carriers, and regular screening remains an option for those who choose not to pursue surgery.
How BRCA Status Affects Cancer Treatment
Knowing your BRCA status matters even after a cancer diagnosis, because it opens up a targeted class of drugs called PARP inhibitors. Here’s the logic: BRCA mutations mean your cancer cells already have a broken DNA repair system. PARP is a separate protein that cancer cells use as a backup repair pathway. PARP inhibitors block that backup, leaving cancer cells with no reliable way to fix their DNA. The damage accumulates and the cells die. Healthy cells, which still have other working repair pathways, are largely spared.
This approach is sometimes described as exploiting the cancer’s own weakness. PARP inhibitors are now used to treat BRCA-related breast, ovarian, pancreatic, and prostate cancers. They are typically taken as pills rather than through infusion, which makes them more manageable for many patients compared to traditional chemotherapy.
Who Should Consider Genetic Testing
Genetic testing for BRCA mutations involves a blood or saliva sample and is widely available. Not everyone needs it, but certain patterns in your family history are strong signals. These include a first-degree relative (parent, sibling, child) with breast cancer before age 50, multiple relatives on the same side of the family with breast or ovarian cancer, a male relative with breast cancer, a relative with cancer in both breasts, or any family member already known to carry a BRCA mutation. Ashkenazi Jewish ancestry alone is considered enough reason to discuss testing with a healthcare provider.
If you test negative but have a strong family history of cancer, that does not necessarily mean you are at average risk. Other genes beyond BRCA1 and BRCA2 can elevate cancer risk, and multi-gene panel testing can look at dozens of them simultaneously. A genetic counselor can help interpret the results, especially when a test returns a “variant of uncertain significance,” a result that means a change was found but its effect on cancer risk is not yet known.