What is genetic testing for hereditary cancer?
Genetic testing for hereditary cancer involves looking at your DNA for genetic variants that could increase your risk of developing certain types of cancer (called “pathogenic variants” or “mutations.”). Genetic testing is usually done on a blood or saliva sample, but other types of samples can be used. Your sample is collected and sent to a specialized laboratory for testing.
Your genetic counselor or other healthcare provider can discuss different types of tests that are available. These include:
- Test focused on genes related to the cancers in your family. Some benefits of a smaller targeted panel is that there is lower likelihood of a variant of uncertain significance or identification of a risk with unclear relevance to the family and unclear recommendations for surveillance and prevention. This testing may miss a relevant mutation, but additional testing could be pursued in the future.
- Guidelines-based panel that includes genes related to several common cancers (breast, ovarian, colon, prostate). Some benefits of a broader panel include the possibility of uncovering other significant cancer risks that are not suspected based on family history, the ability to rule out risk in more genes and therefore provide reassurance and keep testing current for longer. The genes on this test are relatively well-studied, and there are standard guidelines for cancer screening and prevention. With larger panels, there is a higher chance of a variant result or a finding with unclear risk and relevance.
- An expanded cancer panel. We use this type of test more in cancer patients or people who have rare cancers in the family. This panel will include some genes associated with rare cancers ***that are not in your family and also genes that might have a risk of cancer, but we don't have detailed data on the risks or clear guidelines about appropriate cancer screening and prevention. With larger panels, there is a higher chance of a variant result or a finding with unclear risk and relevance.
Possible Types of Genetic Test Results for Each Gene Tested:
- Positive – If a pathogenic variant (mutation) is found, the patient may have an increased risk to develop certain types of cancer in the future, and allow for modifications to their screening plan with the goal of cancer prevention and/or early detection. The identification of a pathogenic variant can have implications for family members and genetic testing for relatives could help determine their cancer risks
- Negative – In a family where there is a known pathogenic variant causing cancer, a negative result is considered a “true negative” and means that person is not at increased risk of cancer from that pathogenic variant. In other families, if no pathogenic variant (mutation) is found, this would significantly decrease the likelihood of the patient having an inherited predisposition to cancer associated with the gene(s) tested. The possibility of a missed pathogenic variant, or a pathogenic variant in another gene not included in the test cannot be eliminated. Other informative family members may be encouraged to seek genetic counseling and consider testing.
- Variant of Unknown Significance (VUS) – This is when a variation in a gene is noted and there is not enough information to determine whether this change increase the chances of developing cancer. The majority of VUS's will be reclassified as benign, meaning that they are likely to represent normal human variation and do not increase cancer risk. VUS results are common and should not be used to make health decisions.
What is genetic counseling?
Genetic counseling is the process of advising individuals and families affected by or at risk of gene pathogenic variants to help them understand the implications of their gene pathogenic variants and hereditary cancer risk. A genetic counselor works with each individual on how genetic testing fits into their medical care, makes cancer screening recommendations, and provides counseling on the potential medical and personal impact of genetic testing and living with a gene pathogenic variant. A genetic counselor is board-certified and state-licensed, with extensive training and experience in hereditary cancer.
Who should consider genetic testing?
The Hereditary CancerRisk Calculator has been developed using NCCN criteria to provide individuals with recommendations for genetic testing.
Your chance of having a pathogenic variant depends on many things, including if there is a pathogenic variant in your family and how you are related to the family member with the pathogenic variant, your personal medical history, and family history of cancer. Genetic testing for hereditary cancer is typically recommended for individuals with a strong family history of certain types of cancer, especially if the cancers occurred at younger ages or if multiple family members have had the same or related types of cancer. Discussing your family history with a genetic counselor can help determine if genetic testing is appropriate for you.
Do people who already have had cancer need a genetic test?
Genetic testing is helpful for people who have already had cancer. In some cases, the genetic test results can help your doctors choose specific treatments for your type of cancer. Genetic testing can also help people take steps to detect or prevent future cancers for themselves or their family members.
What if I test positive for a pathogenic variant?
A positive genetic test result means that you have an increased chance of developing certain types of cancer. A positive test does not mean that you have cancer or are guaranteed to get cancer. Our health care team at UCSF will evaluate your risks based upon your genetic testing results, family history, and other specific risk factors and discuss your goals of care to recommend appropriate options and a risk management care plan for you. False positives are very unlikely. Extensive research has proven that a positive test result is accurate and trustworthy.
Is genetic testing affordable and will insurance cover it?
Costs can vary. Many insurance companies will cover testing and associated genetic counseling when there is a significant family history of cancer or a known familial gene pathogenic variant. The cost of accompanying genetic counseling is often covered by insurance, though there still may be some out of pocket costs.
Does testing positive for a pathogenic variant affect my medical insurance?
Insurance rates and premiums will not go up do to a positive test result because multiple state and federal laws provide legal protection from genetic discrimination, including GINA (Genetic Information Nondiscrimination Act), HIPAA (Health Insurance Portability and Accountability Act), and the ACA (Affordable Care Act).
What if I don’t want to do genetic testing right now?
If, after genetic counseling, you decide that it is not the right time for you to have genetic testing, the counselor can still discuss cancer screening and prevention. If you are closely related to the family member with a gene pathogenic variant, the counselor will usually recommend following guidelines for increased cancer screening, as if positive. However, genetic testing is recommended before considering other risk management methods.