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Genetic testing for inherited cancer risk is a crucial tool in understanding and managing the potential for developing certain types of cancer. This testing identifies specific inherited changes, known as mutations or pathogenic variants, in genes that can elevate the risk of diseases like cancer. It is estimated that approximately 5% to 10% of all cancers are linked to harmful genetic changes passed down from a parent. While some cancers may seem to run in families due to shared environmental factors or behaviors, certain patterns in family history—such as the types of cancer, ages of diagnosis, and other non-cancer conditions—can indicate the presence of an inherited harmful genetic change.
Many genes associated with increased cancer risk have been identified, and individuals with such changes may be diagnosed with a hereditary cancer syndrome. Genetic testing typically involves analyzing blood or saliva samples to determine if an individual carries an inherited harmful genetic change. This process is distinct from tumor genetic testing, which examines genetic changes acquired during a person’s lifetime and is primarily used to guide treatment decisions.
Healthcare providers, including genetic counselors and doctors, usually order genetic tests after reviewing an individual’s personal and family medical history to identify potential inherited cancer patterns. The samples are sent to a genetic testing laboratory, and results are generally available within two to three weeks. Most health insurance plans cover genetic counseling and tests deemed medically necessary, while uninsured individuals may find affordable options through subsidized programs. It is advisable to discuss costs and insurance coverage with a healthcare provider and insurance company prior to testing.
Clinical practice guidelines recommend genetic testing for individuals diagnosed with specific cancers, including triple-negative breast cancer, ovarian cancer, pancreatic cancer, colorectal cancer before age 50, metastatic prostate cancer, or male breast cancer. Understanding whether a cancer diagnosis is linked to an inherited genetic change can help in selecting the most effective treatment and may also have implications for blood relatives.
Testing is also recommended for individuals with personal or family medical histories that suggest a hereditary cancer syndrome. Indicators for testing include having a family member with a known inherited harmful genetic change, being diagnosed with cancer at a young age, having multiple different types of cancer, or having cancer diagnosed in multiple family members, particularly first-degree relatives. Other factors include specific cancer combinations in the family, rare cancer types, and being part of a racial or ethnic group with an increased risk for certain syndromes.
There are several types of genetic tests available, with multigene (panel) tests being commonly used when no known gene mutation exists in a family. These panels can focus on genes associated with specific cancer types or cover a broader range of genes linked to various common cancers, depending on the individual’s history and preferences. If a gene variant is already known in the family, testing may concentrate on that specific variant or the entire gene.
The results of genetic testing can be categorized as positive, negative, true negative, uninformative negative, or variant of uncertain significance (VUS). A positive result indicates a genetic change associated with an increased risk of cancer, which can confirm the cause of cancer in affected individuals and guide treatment. For those without cancer, a positive result signifies an increased risk for the future and can inform management strategies, including enhanced screening, risk-reducing medications, or lifestyle changes.
Conversely, a negative result means no harmful genetic changes were found in the tested genes, which is most informative when a specific disease-causing variant is known in the family. An uninformative negative result occurs when a person with a strong family history tests negative, indicating that an undetected variant may still exist. A VUS is a genetic change with insufficient data to determine its impact on cancer risk and is typically not used for healthcare decisions.
Genetic counseling is highly recommended before and potentially after genetic testing. A trained genetic counselor or healthcare professional can assess the likelihood of inherited risk, discuss the appropriateness and implications of testing, and help individuals understand their options. This counseling also addresses the potential impact of test results on family members, who may have differing views on learning their genetic risk.
While genetic testing offers numerous benefits, such as peace of mind from a true negative result and informed management of cancer risk, it also carries potential downsides. These include psychological stress from a positive result, uncertainty from uninformative results, and privacy concerns regarding genetic information. Legal protections, such as the Genetic Information Nondiscrimination Act (GINA), exist to prevent discrimination based on genetic information in health insurance and employment, although they do not cover all types of insurance.
As research continues to advance in the field of genetics, the understanding of cancer risks associated with specific variants is expected to improve. Despite the recommendations for testing in certain cancer diagnoses, testing rates remain low, potentially due to limited access to genetic counselors and a general mistrust or uncertainty surrounding genetic testing. By increasing awareness and understanding of genetic testing for inherited cancer risk, individuals can make informed decisions about their health and the health of their families.
