Genetic testing for breast cancer predisposition identifies specific inherited changes in a person’s DNA that increase their lifetime risk of developing the disease. The most commonly known mutations are found in the BRCA1 and BRCA2 genes, though testing often includes a panel of other related genes. This testing is not a diagnostic tool for existing cancer, but rather a predictive measure that provides an estimate of future risk.
Determining Eligibility for Testing
The decision to pursue genetic testing is filtered by established medical guidelines that identify individuals who stand to benefit most from the information. These criteria, set by organizations like the U.S. Preventive Services Task Force (USPSTF) and the National Comprehensive Cancer Network (NCCN), focus on personal and family history. A recommendation often begins with a strong family history, such as multiple relatives on the same side of the family diagnosed with breast, ovarian, pancreatic, or high-grade prostate cancer.
Specific personal factors also trigger the recommendation. These include a breast cancer diagnosis at a young age, typically 45 or younger, or the presence of triple-negative breast cancer diagnosed before age 60. Additionally, a diagnosis of male breast cancer or having a known BRCA1 or BRCA2 mutation already identified in a close blood relative meets the criteria.
These guidelines serve as an initial assessment, often performed using a brief risk assessment tool. Individuals who screen positive are then recommended for formal genetic counseling to further evaluate their risk and discuss the implications of testing.
Interpreting Genetic Test Results
Once the test is performed, a person may receive one of three primary categories of results, each carrying distinct implications for future medical management.
The most straightforward result is Positive, meaning a pathogenic or likely pathogenic mutation, such as in BRCA1 or BRCA2, has been identified. This finding confirms an elevated lifetime risk for specific cancers and provides actionable information for risk reduction strategies.
Conversely, a Negative result indicates that no known pathogenic mutations were found in the genes tested. While reassuring, this outcome does not completely eliminate cancer risk, as most breast cancers are not due to inherited mutations. This result means the individual’s risk is likely closer to that of the general population.
The third possible result is a Variant of Uncertain Significance (VUS), which identifies a change in a gene sequence whose effect on cancer risk is not yet known. A VUS is neither clearly harmful nor clearly harmless and does not typically change medical management decisions. The presence of a VUS is more common when testing involves large panels of genes.
Preventative Measures Following a Positive Result
The value of genetic testing for those with a pathogenic mutation lies in the availability of highly effective risk-reduction strategies. These strategies fall into two main categories: enhanced surveillance protocols and proactive risk-reducing interventions.
Enhanced surveillance aims for early detection and involves more frequent and advanced imaging, typically beginning at a younger age than standard screening. For women with a BRCA1 or BRCA2 mutation, surveillance often involves alternating annual mammograms and breast magnetic resonance imaging (MRI), sometimes starting as early as age 25. This dual approach increases the chance of finding cancer at its earliest, most treatable stage.
The most impactful intervention is risk-reducing surgery, which includes prophylactic bilateral mastectomy. Studies show this procedure can reduce the risk of developing breast cancer by 90 to 95 percent in mutation carriers.
Another surgical option is a prophylactic bilateral salpingo-oophorectomy, which involves removing the ovaries and fallopian tubes. This procedure significantly reduces the risk of ovarian cancer by 80 to 90 percent. When performed in premenopausal women, it also reduces breast cancer risk by removing the source of estrogen.
Chemoprevention, using medications such as Tamoxifen or Raloxifene, offers a non-surgical method of reducing breast cancer risk. These drugs work by blocking the effect of estrogen on breast tissue and can reduce the risk by approximately 50 percent.
Financial and Emotional Considerations
The cost of genetic testing has decreased significantly, but the expense still warrants careful consideration. Most health insurance plans, including those covered by the Affordable Care Act (ACA), cover the full cost of genetic counseling and testing for individuals who meet the established criteria. For high-risk individuals, out-of-pocket costs are often minimal or zero.
However, if a person does not meet the established guidelines, insurance coverage can be uncertain, and the cost of a comprehensive gene panel test can be substantial. The emotional aspect of genetic testing is equally important, as receiving information about a high cancer risk can generate significant anxiety and stress. Genetic counseling is strongly recommended before and after testing to help manage these feelings and facilitate informed decision-making.