The vast majority of cancers do not have a strong hereditary link, but for people who have been diagnosed with cancer or have a significant family history of the disease, genetic testing can often shed light on the cause of the disease or an individual’s likelihood of developing it or other cancers. This information can be critical in determining how the disease is treated or how at-risk people can lower their risk, according to Jill Stopfer, MS, LGC, associate director of Genetic Counseling at Dana-Farber’s Center for Cancer Genetics and Prevention.
For people with a personal history of cancer – who have been diagnosed with the disease, either recently or years earlier – genetic testing can help doctors better understand the biology of the disease and decide how best to treat it. For example, a woman who develops breast cancer before age 50, and has several relatives previously diagnosed with breast or ovarian cancer, may have an inherited predisposition to the disease. If testing reveals that she carries a mutation in a cancer-linked gene such as BRCA1 or BRCA2, she may be at high risk of developing a second cancer. Armed with this information, she may decide to take additional steps to prevent another cancer from occurring, which could include going for more frequent screenings, taking a medicine to reduce the chance of a second cancer, or undergoing surgery to remove tissue, such as breast or ovarian, where cancer is more likely to emerge.
Genetic testing may also be recommended for people who, though not diagnosed with cancer themselves, have a family history of the disease that suggests an inherited susceptibility. “Features of a significant family history include the development of cancer in several individuals across multiple generations, particularly if the cancer is diagnosed at an earlier age than is typical for that type of cancer, and if individuals have had multiple cancers or a rare cancer,” Stopfer explains.
If a person tests positive for an inherited cancer mutation, a variety of actions may be in order, she continues. One is to let close relatives – siblings, children, cousins, nephews, and nieces – know of the results. They may wish to undergo genetic testing themselves to learn if they carry the mutation. The decision of whether to take preventive steps, such as special screening, surgery or medication, is different for everyone, and may be influenced by the extent of the risk associated with a particular mutation. For example, an individual may respond differently to a mutation that raises the risk of colon cancer by 80 percent than to a mutation that raises it by only 20 percent. Talking with a genetic counselor can help individuals decide on a course of action that makes the most sense for them, Stopfer says.
Genetic testing is often covered by health insurance, and genetic counselors can provide patients with information about getting genetic testing covered.
“Once informed about the benefits, risks, and limitations of genetic testing, each person can make an individual decision about whether to be tested, and when,” Stopfer observes. “The overall goal in obtaining this information is to gain insights that could lead to better, tailored, health care decisions, maximizing the chances of good health for the extended family.”
Learn more about genetic counseling and testing at Dana-Farber.