Genetic Testing for Cancer
What genetic testing is and can do, and questions to consider if you're thinking of getting tested to learn your risk of developing certain cancers.
If your doctor could tell you whether your odds of getting a specific cancer were high, would you want to know?
Advances in the genetics of cancer make such a prediction possible. Whether you want to know depends on you.
Scientists have learned that all cancers originate from changes in a person's genetic material, which controls everything from the color of your eyes, to whether you can roll or "flip" your tongue, to whether you have a predisposition to a specific genetic disease.
Our genes are inherited from our parents. We inherit two copies of each gene, one from our mother and one from our father. Although all cancers occur because of changes in a person's genes, most cancers are not hereditary. However, having a hereditary predisposition - that is, having a strong family history of cancer - may determine a person's genetic susceptibility for cancer.
Doctors now can test for genetic susceptibility for breast, ovarian, or colon cancer. Genetic tests (which are mostly blood tests) are most often offered to members of families at high risk for genetic conditions. But being predisposed to a disease doesn't necessarily mean you will get the disease. It just means you have an increased risk of getting the disease.
For example, a woman who has a first-degree relative (mother, sister, or daughter) who has breast cancer has twice the risk of getting breast cancer than a woman who does not have a family history of breast cancer. Or, a woman who tests positive for genetic alterations (called mutations) in the BRCA1 (Breast Cancer 1) gene would have a 55 percent to 85 percent chance of developing breast cancer by age 70.
If you are thinking about genetic testing, consider what the pros and cons of testing are for you. You might also want to talk it over with family members, since genetic testing can affect relationships with them. And certainly, you want to be sure to talk with your doctor, genetic counselor, or other health professionals. The American Cancer Society recommends that genetic counseling be done before genetic testing. You may want to get more than one opinion.
What are the benefits of testing?
Genetic testing may help you to:
- Make medical and lifestyle choices.
- Find out you do not have an altered gene.
- Cope with your cancer risk.
- Decide whether to have prophylactic, or preventive, surgery such as prophylactic mastectomy (removal of a breast) or oophorectomy (removal of one or both ovaries).
- Provide useful information to other family members (if you decide to share your results).
- Contribute to research.
What are the disadvantages?
- There is no proven way to reduce genetic cancer risk, except through periodic examination and/or surgery.
- There is no guarantee that test results will remain private.
- You may face discrimination in health insurance, life insurance, or employment.
- You may find it harder to cope with your cancer risk knowing the results.
- Negative results may provide a false sense of security because you think you have no chance of getting cancer, which is not true.
- Genetic testing requires genetic counseling.
- It is costly and may not be covered by your insurance.
What questions should I ask my doctor or genetic counselor?
Here are some questions to consider if you are thinking about getting tested:
- What are the chances that a gene alteration is involved in the cancer in my family?
- What are my chances of having an altered gene?
- Are all genetic tests the same? How much does the test cost? How long will it take to get my results?
- What are the possible results of the test?
- What would a positive result mean for me?
- What would a negative result mean for me?
- How might a positive test result affect my health insurance? Life insurance? Employment?
- Do I want to submit my test results to an insurance company? If yes, will they pay for the testing?
- Where will my test results be recorded? How might this affect me? Who has access to them?
- Will having the test mean a change in my current health practices?
- What type of cancer screening would be recommended if I don't get tested?
What should I discuss with my family?
Genetic tests don't just affect an individual; they can affect an entire family. You have to consider whether you want to disclose this information to them or not. Here are some questions to think about and discuss with your family:
- What effect will the test results have on me and on my relationships with my family?
- Should I share my test results with my partner? Parents? Children? Friends?
- Are my children ready to learn new information that may one day affect their health?
How do I find a genetic counselor?
Major medical centers offer genetic services and some outlying hospitals offer coordinated services through them. Check with your doctor or local hospital to connect with a genetics counselor.
The National Cancer Institute's (NCI) Genetics Services Directory provides a partial list of individuals involved in cancer risk assessment, genetic counseling and testing, and other related services. The directory is available on the CancerNet Web site (see below for link).
Also, the National Society of Genetic Counselors, Inc. has as searchable database to assist consumers in locating genetic counseling services (see below for link).
What can I expect from a genetic counselor?
Genetic counselors can speak to you about complex scientific and emotional topics. You can expect the genetic counselor to have specialized knowledge and be able to answer your questions, maybe even to anticipate some of your questions. Often, the genetic counselor acts as an interpreter for the medical information, and as a support person if the information turns out to be stressful for you. Your genetic counselor may ask extensive questions about your family history to understand inheritance patterns.
Will a genetic counselor tell me what to do?
No, a genetic counselor's primary concern is helping you reach decisions which are appropriate for you, or help you understand and adjust to complex information, uncertainties, or new diagnoses.
Where can I get a genetic test?
All genetic tests have to be ordered by a physician. The tests can be provided by commercial labs or by clinical services within a hospital. All test results should be discussed with a genetic professional.