The BRCA1 and BRCA2 genes are specific DNA segments found in every person. These genes are involved in the body’s natural processes to maintain cellular health. When these genes function as intended, they help protect against uncontrolled cell growth. However, changes or “mutations” in these genes can disrupt their normal activity. Such mutations are linked to an increased likelihood of developing certain types of cancer, affecting individuals across their lifetime.
The Role of BRCA Genes
BRCA1 and BRCA2 are recognized as tumor suppressor genes, meaning their normal function helps prevent the formation of tumors. These genes play a significant role in DNA repair, particularly in fixing double-stranded breaks through a process called homologous recombination repair, which maintains genetic integrity.
When a harmful mutation occurs in either BRCA1 or BRCA2, these genes may not work effectively. This impaired function means that cells are less able to repair damaged DNA, leading to an accumulation of genetic errors. This increases the risk of cells growing uncontrollably, contributing to an elevated risk of developing specific cancers.
Understanding Cancer Risks
Mutations in the BRCA1 and BRCA2 genes are associated with an increased lifetime risk for several types of cancer. The most notable associations are with breast and ovarian cancers. For women with a BRCA1 mutation, the estimated lifetime risk of developing breast cancer by age 70 is approximately 55-65%. For those with a BRCA2 mutation, the risk is about 45% by age 70. These figures are significantly higher than the general population’s risk.
Beyond breast cancer, BRCA mutations also elevate the risk of ovarian cancer. Women with a BRCA1 mutation face a lifetime risk of ovarian cancer ranging from 39% to 46%, while those with a BRCA2 mutation have a risk between 11% and 17%. This compares to a general population risk of less than 2%. These mutations can also increase the risk for other cancers, including prostate cancer, pancreatic cancer, and melanoma. For example, men with a BRCA2 mutation have a higher lifetime risk of developing male breast cancer (1.8% to 7.1% by age 70) compared to the general male population (0.1%).
Genetic Testing for BRCA Mutations
Genetic testing for BRCA mutations is recommended for individuals with specific personal or family histories of cancer. This includes those with a strong family history of breast, ovarian, pancreatic, or prostate cancer, especially if these cancers occurred at younger ages. Individuals diagnosed with certain types of cancer, such as triple-negative breast cancer before age 50, may also qualify for testing.
The testing process usually begins with genetic counseling, where a healthcare professional discusses the implications of testing, potential results, and family history. A sample for testing is then collected, most commonly through a blood draw or a saliva sample. The laboratory analyzes the DNA from the sample to identify any harmful mutations in the BRCA1 or BRCA2 genes. A positive result indicates the presence of a pathogenic variant, signifying an increased cancer risk. A negative result means no known harmful mutation was found, but its interpretation depends on the individual’s family history and whether a specific mutation was already identified in the family.
Managing Risk with BRCA Mutations
For individuals who test positive for BRCA mutations, various strategies are available to manage their elevated cancer risk. Increased surveillance is a common approach, involving more frequent and intensive screenings. This often includes annual mammograms and breast magnetic resonance imaging (MRI) for breast cancer detection, starting at a younger age than standard guidelines. For ovarian cancer, surveillance may involve transvaginal ultrasound and blood tests for CA-125, though the effectiveness of these for early detection is still being studied.
Prophylactic surgeries are another option for risk reduction. A prophylactic bilateral mastectomy can significantly reduce breast cancer risk by approximately 90% in women with BRCA mutations. Similarly, a prophylactic oophorectomy can reduce ovarian cancer risk by about 80% and also lower breast cancer risk. This procedure is often considered after childbearing is complete, generally between ages 35-40 for BRCA1 carriers and 40-45 for BRCA2 carriers.
Chemoprevention, using medications to reduce cancer risk, may also be considered. Drugs like tamoxifen or raloxifene can reduce the risk of estrogen receptor-positive breast cancer in high-risk women. Lifestyle considerations, such as maintaining a healthy weight, regular physical activity, and limiting alcohol consumption, are also encouraged as they may contribute to overall well-being and influence cancer risk. These management strategies are personalized, and decisions are made in consultation with healthcare providers, considering individual risk factors and preferences.