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Family History and Genetic Risk
A small subset of cancers arise because a person has inherited one copy of a particular gene that does not work properly. It's important to understand your family history of cancer.
Cancer is, by definition a genetic disease, in that many cancers are caused by unexpected changes in individual cells. When these cells are changed, they grow faster than the cells around them. They also gain properties they shouldn't have, allowing them to move beyond their boundaries, invade and grow. That's the definition of cancer: cells growing out of control and invading the spaces around them.
These changes -- or mutations -- in genes can occur during the course of a person's life. But, there's a small subset of cancers that arise because a person has inherited one copy of a particular gene that does not work properly.
Inherited genetic mutations play a major role in about 5 to 10 percent of all cancers. Researchers have associated mutations in specific genes with more than 50 hereditary cancer syndromes, which are disorders that may predispose individuals to developing certain cancers.
Genetic tests for hereditary cancer syndromes can tell whether a person from a family that shows signs of such a syndrome has one of these mutations. These tests can also show whether family members without obvious disease have inherited the same mutation as a family member who carries a cancer-associated mutation.
Some of the cancers caused by inherited genes are:
breast cancer
colon cancer
endocrine cancer
melanoma (and other forms of skin cancer)
ovarian
pancreatic cancer
prostate cancer
The National Cancer Institute provides a list and resources for the known Familial Cancer Susceptibility Syndromes
What are some of the features of inherited cancer in families?
- Cancer was diagnosed at an unusually young age
- Several different types of cancer occurred in the same person
- Cancer in both organs in a set of paired organs, such as both kidneys or both breasts
- Several first-degree relatives (the parents, siblings, or children of an individual) have the same type of cancer (for example, a mother, daughter, and sisters with breast cancer); family members with breast or ovarian cancer; family members with colon cancer and endometrial cancer
- Unusual cases of a specific cancer type (for example, breast cancer in a man)
- The presence of birth defects that are known to be associated with inherited cancer syndromes, such as certain noncancerous (benign) skin growths and skeletal abnormalities associated with neurofibromatosis type 1.
- Being a member of a racial or ethnic group that is known to have an increased risk of having a certain inherited cancer susceptibility syndrome and having one or more of the above features as well
- Several family members with cancer
If any of the above sounds like your family, consider being referred to a genetic specialist. A genetic specialist can be a physician or a genetic counselor with trained in the diagnosis and management of these inherited cancer syndromes.
In the setting of families where there is more breast cancer than one would expect to see by chance, or where you see clusterings of breast and ovarian cancer, consider clinical genetic testing. In general, the best person to start testing is the one with a cancer diagnosis. By identifying the inherited mutation in the gene, testing of other family members is much easier.
Testing positive for a genetic mutation does not guarantee cancer will develop
Everyone inherits two copies of every gene. If one copy has a mutation the other one is the "backup." If anything should happen to the backup, then the chances of cancer increase. For that reason, knowing you have an altered or mutated gene enables your doctors to follow you more carefully throughout your life.
Get more information about genetic testing:
To learn about genetic testing at the Rogel Cancer Center, please visit our Cancer Genetics webpages. You'll learn how to make an appointment and what to expect.