Is cancer hereditary? For the most part, the answer is no. Only about 5 to 10% of cancers are hereditary. These hereditary cancers result from genetic mutations.
Inherited Cancer Mutations
Gene mutations are inherited from the beginning, arising in either the egg or sperm forming the embryo. A child of parents with an inherited cancer mutation has a 50% chance of having the mutation.
Mutations in tumor suppressor genes contribute to hereditary cancers. The most common mutated gene is TP53 that is designed to keep cancer at bay by preventing the uncontrollable cell growth that leads to the disease. If the mutations prevent tumor suppressor genes from telling cells to die at the proper time or repairing DNA errors, cancer cells can proceed unchecked.
Just because a person inherits a gene mutation does not mean they will definitely develop cancer. The likelihood, however, increases significantly.
What Types of Cancer Are Hereditary?
The National Cancer Institute defines hereditary cancer as, “A type of inherited disorder in which there is a higher-than-normal risk of certain types of cancer.” While caused by gene mutations, hereditary cancer is also identified by the patterns within families.
Examples of hereditary cancer include:
- Breast cancer: Most women diagnosed with breast cancer do not have a genetic mutation, but there are exceptions. The most common inherited mutations are BRAC-1 and BRAC-2. Besides breast cancer, types of cancer associated with these mutations are those of the ovaries, pancreas, and prostate, as well as melanoma.
- Cowden Syndrome: This rare hereditary condition greatly increases cancer risk for those affected. Most patients with Cowden syndrome develop non-cancerous growths on the skin or mucous membranes. Some will develop either benign or malignant tumors in the brain, breast, gastrointestinal tract, thyroid or uterus. The PTEN gene mutation associated with this syndrome affects tumor suppression.
- Lynch Syndrome: Also known as hereditary non-polyposis colorectal cancer, those with Lynch Syndrome are more likely to develop colorectal cancer before age 50. These mutations increase the risk of developing brain, endometrial, pancreatic, stomach and urinary tract cancers.
- Familial Adenomatous Polyposis: This inherited disorder is another leading cancer precusor, including colon cancer. Also known as Gardner’s syndrome, this condition leads to a large number of adenomas, or precancerous colon polyps, developing throughout the intestinal tract. These polyps may predispose patients to colon cancer.
These are just a few of the genetic mutations that may lead to cancer. Dozens of others exist.
Hereditary Cancer Considerations
Because cancer is so common, it isn’t unusual for families to experience several members diagnosed with some form of the disease. However, just because various family members have cancer does not mean they have a hereditary type.
For instance, if smoking is prevalent in the family, tobacco use may have triggered cancer. Obesity is a cancer risk factor. So, that could account for a high incidence of cancer in vulnerable families. Family cancer syndrome, also known as hereditary cancer syndrome, differs from simply having a lot of relatives stricken by this dreadful disease.
Not everyone knows their family health history. While that is true of adoptees, is it also the case in which families don’t discuss such issues. Not that long ago, cancer was a stigma that led many people to keep their diagnoses a secret. It’s possible that vagueness about a relative’s cause of death remains because the person did not want anyone to know they had cancer.
If you do not know what caused the death of grandparents or other close relatives, try to find out from family members. If known and suspected cancer deaths are high, hereditary cancer syndrome is a possibility.
Those who suspect they may have inherited a gene mutation causing cancer can undergo genetic testing. Consider genetic testing if any of the following hold true:
- Several first-degree relatives (such as parents or siblings) have the same type of cancer. A mother whose sister and daughter are all diagnosed with breast cancer may share the BRAC-1 mutation.
- Different types of cancer occurred in the same relative.
- Cancer appears in both sets of paired organs, such as both breasts or both kidneys.
- A relative was diagnosed with cancer while young. A person diagnosed with colon cancer in their 80s is less likely to have hereditary cancer than someone diagnosed in their 30s.
The genetic testing process is straightforward. A blood, saliva or skin cell sample is obtained and sent to a laboratory for genetic testing. The results are returned to the party ordering the testing, usually a doctor or genetic counselor.
A negative test indicates that an inherited gene mutation is not present. If positive, the person can learn more about their risks and possible preventive measures. When the individual has already received a cancer diagnosis, knowing the genetic component can help their oncologist determine treatment options. Health insurance will usually pay for genetic cancer testing.
For more than 70 years, Yosemite Pathology and Precision Pathology has advanced anatomic pathology in the Western United States. Today, our practice encompasses more than 20 board certified anatomic pathology specialists. We offer a broad range of specialties including breast, gynecologic, hematology, thyroid, urologic and other pathologies. For more information about our services, contact us today.
Jane Meggitt’s work has appeared in dozens of publications including USA Today, Zack’s, Financial Advisor, nj.com, The Houston Chronicle and The Nest. She is a graduate of New York University.
American Cancer Society – Family Cancer Syndromes
Cancer.net – The Genetics of Cancer
Canadian Cancer Society – Check your family history
Yale Medicine – Inherited Cancers
MD Anderson Cancer Center – Hereditary Cancer Syndromes
American Cancer Society – What Causes Colorectal Cancer?
American Cancer Society – Family Cancer Syndromes