From the DFCI/NCCN Cancer Survivorship Information^TM

We know that cancer can run in families, and that close relatives of someone with cancer may be at greater risk of getting it themselves. Genetic testing can be used to learn more about this risk. It can also be useful for cancer survivors, because it may allow them to prevent future cancers by undergoing increased screening, taking medication, or having preventive surgery.

For example, someone at high risk of colon cancer could lower his risk by having colonoscopies. A person who knows she is at risk of breast cancer might decide to take tamoxifen.
Genetic testing can be helpful for family members of cancer survivors, as well. If you have a strong family history of cancer, ask your health care team for a referral to a genetic counselor.

Genetic Testing and Counseling

In some cases, families with a high risk of cancer can have genetic testing. The goals of testing are to:

measure a family’s likelihood of developing a hereditary cancer (a cancer that can run in the family)
provide an accurate overview of their cancer risk
make suggestions about what they should do to lower their cancer risk

Genetic testing is available for several of the hereditary cancers. These include cancers of the breast, colon, and ovaries.

A person who wants to be tested will first have a genetic counseling session. This session is used to determine whether or not he or she is eligible for the tests. A genetic counselor will also explain the benefits and risks of testing other family members for cancer genes.
If the family decides to move forward, blood is taken from the patient and/or family members and sent to a lab to be analyzed. Depending upon the test, it can take up to a few months for genetic test results to become available. All genetic counseling sessions and blood test results are confidential.

Potential Risks of Genetic Testing for Cancer Survivors

Although people may find genetic counseling sessions helpful, talking about their family’s risk of cancer may make people feel stressed or anxious. Describing the family’s experience with cancer may bring up painful memories of relatives who have been diagnosed with or died from cancer. Any patient who feels stressed, anxious, or depressed as a result of genetic testing and counseling can talk with a social worker or psychologist.
Some people may worry that employers or insurers could use genetic test results to discriminate. There are bills in Congress that aim to keep this from happening, but right now there is no protection at the national level. Some states have laws that prevent genetic discrimination on the job and restrict employers’ ability to see genetic test results. The Health Insurance Portability and Accountability Act (HIPPA) provides some protection against discrimination under group insurance plans.