Is Cancer Hereditary?
Inherited Cancer Syndromes
About 5 percent to 10 percent of all cancer cases occur in someone who inherited a genetic mutation that increases cancer risk.
The mutations and syndromes that are discussed in cancer care are:
BRCA1 and BRCA2 Genetic Mutations
A woman who inherits a BRCA (BReast CAncer) genetic mutation has an increased risk of developing breast and ovarian cancer. A man who inherits a BRCA mutation has an increased risk of developing breast and prostate cancer.
This syndrome is the result of mutations in the PTEN gene. A woman with this syndrome is at increased risk of developing breast and uterine cancer. The mutations also put women and men at increased risk of thyroid cancer.
Familial Adenomatous Polyposis
This syndrome is caused by mutations in the APC gene. These mutations increase the risk of colorectal cancer. They also can increase the risk of soft tissue tumors and brain tumors.
Most people with Li-Fraumeni syndrome, a rare genetic condition, have mutations in the TP53 gene, increasing the risk of many different types of cancer. The most common are soft tissue sarcomas (tumors in fat, muscles, nerves, joints, blood vessels, bones or deep skin), breast cancer, leukemia, lung cancer, brain tumors and adrenal gland cancer.
Also referred to as hereditary nonpolyposis colorectal cancer (HNPCC), this syndrome increases colorectal cancer risk due to mutations in DNA mismatch repair genes called MLH1, MSH2, MSH6 or PMS2. Variations of these mutations can also cause Muir Torre syndrome or Turcot syndrome, increasing the risk for certain skin cancers or brain tumors, respectively.
Multiple Endocrine Neoplasia (MEN)
There are two types of MEN syndrome: MEN1 is caused by a mutation in the MEN1 gene. MEN2A and MEN2B are caused by mutations in the RET gene. All three mutations increase the risk of cancers of the endocrine system.
Von Hippel-Lindau Disease
This disorder, which is the result of mutations in the VHL gene, causes an abnormal growth of blood vessels (called hemangioblastomas or angiomas), and increases the risk of kidney and other cancers.
How Risk Is Inherited
As you may remember from science class, the nucleus of every cell in our body contains 23 pair of chromosomes, which house the genes that make us who we are. One chromosome in each pair comes from our father; the other comes from our mother.
Each chromosome is made up of thousands of genes, which are coded segments of DNA. A change in the sequence of the DNA that makes up the gene can cause the gene to stop functioning normally. These genetic changes are called mutations.
If your parent has a genetic mutation, it does not mean you definitely have it too. Similarly, if you have a genetic mutation, it doesn't mean your child has it. The odds in each case are 50/50. That’s because every person has two copies of every gene: one inherited from dad (who has two copies of the gene), and one inherited from mom (who has two copies of the gene). A parent who has one copy of a genetic mutation will pass on either the mutated gene or the normal gene. And the child’s chance of getting either the mutated version or the normal one is 50/50—like the flip of a coin. If the parents have a second child, that child will also have a 50/50 chance of inheriting the genetic mutation. A parent can pass on the genetic mutation and increased risk even if she or he never develops cancer. A child who does not inherit the abnormal mutation cannot pass it on.
If you inherit a mutation that increases cancer risk it does not mean you are destined to get cancer. It means your risk is higher than average. Knowing you have mutation creates opportunities to decrease the risk through cancer screening and other risk-reduction measures.
Testing for Inherited Cancers
Learning that you have cancer, or that a close relative does, may make you think you should go online and order one of those genetic tests you may have read about or seen advertised. That's not a wise idea.
The first thing you should do is make an appointment to speak with a genetic counselor, who will talk to you about your family’s history and help you decide whether testing is right for you. Seeing a genetic counselor will also allow you to be confident that the right tests are ordered and that the results are interpreted correctly.
Genetic testing typically involves a blood or saliva sample. A special analysis in the lab can detect DNA changes that suggest a mutation. The goal of testing is not just to get a result, but to get information that you can use to help you decrease your risk of getting cancer. For this reason, testing typically begins with the person who was diagnosed with cancer. If your relative doesn’t have an inherited mutation then there is no reason to test his or her children. If she or he does have a genetic mutation, it can be tested for in other family members. Genetic tests do not always give a simple yes or no, which is another reason why it is important to see a genetic counselor.
Children should not be tested unless they are at age when it would make sense to start cancer screening with, say, mammography or a colonoscopy, or to have surgery to reduce the cancer risk.
How to Get Started
- Ask your doctor for a referral to a genetic counselor.
- Find a genetic counselor near you by contacting:
- National Society of Genetic Counselors
- National Cancer Institute: Cancer Genetics Services Registry
- Informed DNA
Payment and Legal Protection
Paying for Genetic Testing
The Affordable Care Act (Obamacare) requires insurance companies to cover genetic testing for women whose family history of breast and/or ovarian cancer suggests they are at high risk of carrying a BRCA1 or BRCA2 genetic mutation. This is the only genetic test expressly covered as a preventive health service.
However, insurance companies will also typically cover tests for genetic mutations that increase cancer risk in patients who have a strong family history of a certain type of cancer or who have a first degree relative who has been tested for and found to have the genetic mutation.
Before you have any genetic test, you should talk to a genetic counselor about the cost of the test and whether your insurance will cover all or part of the cost.
Laws Against Genetic Discrimination
The Genetic Information Nondiscrimination Act of 2008, also referred to as GINA, is a federal law that protects Americans from genetic discrimination in health insurance and employment. The law has two parts. Part one makes it illegal for health insurers to use or require genetic information to make decisions about a person's insurance eligibility or coverage. Part two makes it illegal for employers to use a person's genetic information when making decisions about hiring, promotion, and several other terms of employment.
Under the Affordable Care Act, group health plans can no longer deny insurance based on preexisting conditions and cannot increase premiums based on health status.