The BRCA1 and BRCA2 genes are tumor suppressor genes that help maintain DNA integrity. They produce proteins that repair damaged DNA, preventing uncontrolled cell growth that can lead to cancer. If a person inherits a harmful mutation in either BRCA1 or BRCA2, their ability to repair DNA is compromised. This impairment can lead to genetic errors, increasing susceptibility to certain cancers. Understanding BRCA test results provides valuable information about personal cancer risk.
Understanding Your BRCA Test Results
Genetic testing for BRCA1 and BRCA2 mutations can yield different outcomes, each with distinct health implications.
A positive result indicates a harmful mutation in either BRCA1 or BRCA2 has been detected. This means an individual has an increased likelihood of developing certain cancers, though it does not guarantee a cancer diagnosis.
A negative result signifies no known harmful mutations were found. While reassuring, a negative result does not eliminate all cancer risk. Other genetic factors or environmental influences can still contribute to cancer development.
Sometimes, a test may reveal a Variant of Uncertain Significance (VUS). A VUS refers to a genetic change in BRCA1 or BRCA2 whose effect on cancer risk is not yet clearly understood. These variants require further research and may be reclassified as more scientific data becomes available. Most VUS results are eventually reclassified as benign, meaning they do not increase cancer risk. Until reclassified, medical management of cancer risk is guided by family history and other personal risk factors. Genetic counseling can provide clarity on what each result means for you and your family.
Implications for Cancer Risk
Harmful mutations in BRCA1 and BRCA2 significantly increase lifetime risk for several cancers. The most prominent associations are with female breast cancer and ovarian cancer. For women with a BRCA1 mutation, the estimated cumulative risk of developing breast cancer by age 70 can range from 55% to 65%, while for BRCA2 carriers, it is approximately 45% to 47%.
Ovarian cancer risk is also elevated, with BRCA1 carriers facing a cumulative risk of about 39% by age 70, and BRCA2 carriers having a risk ranging from 11% to 17%. These mutations also increase the risk of other cancers, including male breast cancer, prostate cancer, pancreatic cancer, and melanoma. For example, men with a BRCA2 mutation have an increased risk of prostate cancer, with some studies estimating a lifetime risk up to 61% by age 80.
Inheriting a BRCA mutation indicates an increased predisposition, not a guarantee of developing cancer. Individual cancer risk is influenced by factors such as age, family history, specific mutation type, and lifestyle choices. Large-scale studies provide estimates that help guide risk assessment.
Managing Your Health After BRCA Results
For individuals with BRCA mutations, proactive health management strategies can help mitigate cancer risks. Enhanced surveillance is a common approach, involving more frequent and earlier screenings than recommended for the general population. This may include annual mammograms often combined with breast MRI for breast cancer detection.
For ovarian cancer surveillance, transvaginal ultrasound and CA-125 blood tests may be recommended, though their effectiveness in early detection is still being studied.
Risk-reducing surgeries offer a more aggressive prevention approach. A prophylactic mastectomy, the surgical removal of healthy breast tissue, can reduce breast cancer risk by at least 90% in BRCA mutation carriers. Another surgical option is a bilateral salpingo-oophorectomy, the removal of the ovaries and fallopian tubes, strongly recommended for women with BRCA mutations after childbearing. This procedure significantly reduces ovarian cancer risk and can also lower breast cancer risk by 30-60% in pre-menopausal women.
Additionally, certain medications, known as chemoprevention, can help reduce the risk of developing some BRCA-associated cancers. These personalized care plans are developed in consultation with healthcare providers, including genetic counselors and oncologists, to align with an individual’s specific risk profile and preferences.
BRCA Results and Your Family
BRCA gene mutations are hereditary, meaning they can be passed down through generations. These mutations follow an autosomal dominant inheritance pattern, implying each child of a parent with a BRCA mutation has a 50% chance of inheriting it.
This hereditary nature makes “cascade testing” a valuable strategy. Cascade testing involves offering genetic testing to blood relatives of an identified BRCA mutation carrier. Identifying at-risk family members allows for early intervention and personalized cancer risk management.
Genetic counseling plays a significant role for family members, helping them understand their personal risks, testing options, and result implications. While sharing genetic information can involve ethical and emotional considerations, informing relatives about a familial BRCA mutation can provide life-saving opportunities for screening and prevention.