"A woman generally will be advised to have genetic counseling if she has two or more first-degree relatives with breast or ovarian cancer or both, especially if the breast or ovarian cancer occurred before age 50," says Sandhya Pruthi, M.D., a breast health specialist at Mayo Clinic, Rochester, Minn. First-degree relatives are your parents, sisters, brothers and children.
If you decide to proceed with genetic risk assessment, a genetic counselor or other healthcare professional trained in breast cancer genetics will help you prepare a family tree. This chart, also known as a pedigree, lists members of each generation of your biological family, with all available health and disease information. Ideally, this family tree should go back at least three generations and should include the type of cancer each relative has had, as well as the person's age at diagnosis. But in reality, most people don't have much information before their grandparents' generation. After the family tree has been constructed, the genetic counselor analyzes the pattern of breast cancer in the family.
Your family's pedigree related to breast cancer can be categorized in one of three ways:
Sporadic. This means that your personal or family history of breast cancer doesn't follow any regular pattern of inheritance. Instead, breast cancer appears in a scattered, isolated way. About 70% of all women with breast cancer have a sporadic family pedigree.
Familial. This means that there may be a strong family history of breast cancer, but there is no well-defined pattern to suggest that the breast cancer was passed genetically from one generation to another. About 20% of all women with breast cancer have a familial breast cancer pedigree.
Hereditary. This means that there is a compelling family history, including multiple blood relatives with breast and/or ovarian cancer. That pattern strongly suggests an inherited form of the disease. Heredity accounts for about 10% of all breast cancers, and abnormal BRCA1 and BRCA2 genes explain many of these cancers. However, other genes that have not been discovered yet are probably also involved in hereditary breast cancer.
Several issues need to be considered before deciding to undergo genetic testing:
Judging the need for genetic testing. Experts generally agree that women with the sporadic category of family history will not benefit from the genetic test. Women with the familial category of family history are at moderate risk and will probably not be encouraged to get the test. If your family history suggests the hereditary category of breast cancer, you may decide to take the breast cancer gene test.
Complex emotional and legal questions. Think about how testing might affect you or your healthcare choices. In considering genetic testing, talk with your doctor about a consultation with a genetic counselor.
Learning your genetic profile. In weighing the risks and benefits of genetic testing, ask yourself this fundamental question: do you really want to know the results? Consider how you might feel if you find out that you have a BRCA gene mutation.
Accuracy of the test. Current techniques don't easily allow for studying the gene in such a way that the mutation can be found, even when a BRCA mutation exists. In that case, a negative test might be falsely reassuring. Such a false-negative result means the test shows you don't have a mutated gene, when you actually do. Discuss with your doctor and genetic counselor what negative test results might mean for you, given your personal and family history of breast cancer.
Insurance aspects of genetic testing. If you've already had cancer, you may have trouble getting new health insurance, and the results of your genetic testing aren't likely to affect your obtaining new health insurance. However, if you haven't had cancer, and you are considering testing to see if you carry a high-risk gene, you might want to make any changes to your insurance before undergoing testing. Most states have enacted laws to ensure that your genetic information can't be used to deny you health insurance coverage, but health insurers do have some legal protections.
Limited prevention methods. If you find out that you have an altered BRCA gene, you may wish to consider preventative measures. No method, however, is 100% effective in preventing cancer, and some existing methods, such as preventive mastectomy, may be unacceptable to you.
Expense. Genetic testing is expensive. Testing may cost several hundred dollars if you have a family history with a known mutation (for example, if a close relative has a BRCA mutation). However, if you're unaware of your genetic history, comprehensive testing may cost several thousand dollars. Insurance may cover appropriate candidates for testing, but genetic testing is not always included in your insurance policy. Consider contacting your insurance company to see if your testing expenses will be covered.