BRCA1 is a gene that helps your cells repair damaged DNA. When it works normally, it acts as a tumor suppressor, catching and fixing broken strands of DNA before they can lead to uncontrolled cell growth. When someone inherits a harmful change (mutation) in this gene, their cells lose that repair ability, and their lifetime risk of developing breast cancer jumps from about 13% to over 60%. The gene’s full name, BReast CAncer gene 1, reflects the strong connection to breast cancer, but mutations in BRCA1 also raise the risk of ovarian cancer and several other types.
How BRCA1 Protects Your DNA
Your DNA takes damage constantly, from sunlight, normal cell division, and chemical processes inside the body. One of the most dangerous types of damage is a double-strand break, where both sides of the DNA ladder snap apart. Left unrepaired, these breaks can cause cells to grow abnormally.
BRCA1 is central to a repair process called homologous recombination, the most precise method your cells have for fixing double-strand breaks. The BRCA1 protein pairs with a partner protein called BARD1, and together they coordinate several steps: they help strip back the broken ends of DNA so the cell can use an intact copy of the gene as a template, then they help load other repair proteins onto the damaged site to rebuild the strand accurately. BRCA1 also protects DNA during normal cell replication, preventing the copying machinery from chewing up stretches of genetic code when it stalls.
When BRCA1 is mutated and can’t do this work, cells default to less accurate repair methods that introduce errors. Over time, those errors accumulate, and the risk of a cell becoming cancerous rises significantly.
Cancer Risks for BRCA1 Carriers
The most well-established risk is for breast cancer. More than 60% of women who inherit a harmful BRCA1 mutation will develop breast cancer at some point in their lives, compared to roughly 13% of women in the general population. BRCA1-related breast cancers also tend to appear at younger ages and are more likely to be triple-negative, a subtype that doesn’t respond to certain hormone-based treatments.
Ovarian cancer risk rises substantially as well. Risk-reducing surgery to remove the ovaries and fallopian tubes is considered the most effective way to address this, because ovarian cancer is notoriously difficult to detect early with screening alone. BRCA1 mutations have also been linked to elevated risks of pancreatic cancer and, in men, prostate cancer, though the absolute risk for these cancers remains lower than for breast and ovarian cancer.
How the Mutation Is Inherited
BRCA1 mutations follow an autosomal dominant inheritance pattern. That means you only need one altered copy of the gene (from one parent) to have an increased cancer risk. If a parent carries a BRCA1 mutation, each of their children has a 50% chance of inheriting it, regardless of sex. Men can carry and pass on BRCA1 mutations even though their own cancer risks are different from women’s.
Certain populations have higher carrier rates due to what geneticists call founder mutations, specific changes that became more common in a group over generations. In the Ashkenazi Jewish population, about 1 in 40 people carry one of the known BRCA1 or BRCA2 founder mutations. One specific BRCA1 mutation (185delAG) has a carrier frequency of roughly 1.09% in this group. These same mutations can appear in other populations, but they’re far less common.
Who Should Consider Genetic Testing
Not everyone needs BRCA1 testing. Guidelines generally recommend it for people whose personal or family history suggests a hereditary pattern. That includes being diagnosed with breast cancer at age 45 or younger, having triple-negative breast cancer before age 60, having multiple close relatives with breast or ovarian cancer, or having a male relative with breast cancer. Male breast cancer at any age is an immediate indication for testing.
The American Society of Breast Surgeons has gone further, recommending genetic testing for all individuals with a personal history of breast cancer regardless of age, family history, or tumor type. Testing typically involves a blood or saliva sample, and results can take a few weeks. A positive result doesn’t mean cancer is inevitable. It means your risk is elevated and that specific screening and prevention strategies become relevant.
Screening for BRCA1 Carriers
If you test positive for a BRCA1 mutation and haven’t been diagnosed with cancer, recommended screening starts earlier and is more intensive than standard guidelines. Breast self-awareness is encouraged starting at age 18, with clinical breast exams every 6 to 12 months beginning at age 25. Annual breast MRI is recommended from ages 25 to 75, and annual mammography (often with 3D imaging) is added starting at age 30. Staggering these two imaging methods at six-month intervals means you’re getting some form of screening roughly every six months.
For ovarian cancer, there is no reliable screening method comparable to mammography. This is one reason why risk-reducing surgery is discussed early with carriers rather than relying on surveillance alone.
Prevention and Risk Reduction
Preventive (prophylactic) bilateral mastectomy reduces breast cancer risk by at least 95% in women with a harmful BRCA1 mutation. It’s among the most effective prevention options available, though it’s a major decision with lasting physical and emotional effects. Some women choose this route in their 30s or 40s; others opt for intensive screening instead.
Risk-reducing removal of the ovaries and fallopian tubes (salpingo-oophorectomy) is the most effective approach to lowering ovarian cancer risk. It also triggers surgical menopause, which carries its own health considerations, including effects on bone density and cardiovascular health. The timing of this surgery is typically discussed based on whether a woman has completed childbearing and the age at which ovarian cancer risk begins to climb for BRCA1 carriers, which is generally earlier than for the general population.
Targeted Treatment for BRCA1 Cancers
The same DNA repair defect that makes BRCA1-mutated cells prone to cancer also creates a vulnerability that doctors can exploit. A class of drugs called PARP inhibitors works by blocking a backup DNA repair pathway that cancer cells rely on when BRCA1 isn’t functioning. Normal cells can still use BRCA1 to repair themselves, but cancer cells with the mutation cannot, so they accumulate so much DNA damage that they die. This concept is called synthetic lethality: neither the BRCA1 loss nor the PARP blockade alone is lethal to the cell, but the combination is.
Several PARP inhibitors, including olaparib, rucaparib, and niraparib, have been approved for use in BRCA-mutated breast and ovarian cancers. These drugs are taken as pills and represent a significant shift toward precision treatment, where therapy is matched to the specific genetic profile of a person’s tumor rather than relying solely on conventional chemotherapy.