What is hereditary cancer?

All cancers are due to changes in genes. The majority of cancer is due to gene changes acquired during a person's lifetime and is not considered to be inherited or hereditary. But in some cases, a change in a specific gene may have been inherited (hereditary), and can predispose a person to a particular type of cancer. In these cases, cancer is linked to an inherited trait which can be passed on to a person's children, grandchildren and other extended family members. 

Cancer due to an inherited trait results from a change in at least one gene that occurred before conception, and at least one additional change in a gene occurring after conception. A change that occurs before conception can be passed from one generation to the next. Cancers that are not due to an inherited trait are brought about by changes in the genes that occur after conception. 
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How many cancers are due to inherited traits?

One in every 3 people will develop cancer in their lifetime. While the majority of cancer is not due a specific inherited trait, hereditary cancers account for approximately 5 to 10 percent of all cancer cases. 

If an individual inherits a specific, altered cancer susceptibility gene, their lifetime risk for a particular type or types of cancer is significantly increased. Some cancer types, which are known to cluster in families and may be due to an inherited trait, include breast, ovarian, colon and other cancers. 
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Who may be at risk for a hereditary cancer?
Analyzing a family history can help to determine if a person may be at increased risk for a hereditary cancer. Family histories that may indicate hereditary cancer tend to have certain features in common. 

These include:

  1. Cancer in two or more close relatives, on the same side of the family.
  2.  Individuals diagnosed with cancer before the age of 50. 
  3. The presence of the same or associated cancers that comprise a syndrome. For example, breast and ovarian cancer in the same family is suggestive of hereditary breast-ovarian cancer syndrome. 
  4. Bilateral cancer in paired organs, which is cancer in both organs where the body has more than one of a particular organ. For example, cancer in both breasts, or ovarian cancer in both ovaries. 
  5. Two or more separate tumors in the same individual. 
  6. Two or more generations affected on the same side of the family. 
  7. Presence of a rare cancer (for example, male breast cancer). 

If any one of these circumstances describes your family, you may be at increased risk for cancer due to an inherited trait.  back to top 

How is an individual's risk for hereditary cancer determined? 
A person's cancer risk may be derived in a number of different ways. Typically, however, it begins with obtaining a pedigree, or a three generation family history. This involves collecting information about first, second and third degree relatives on both the mother's and father's side of the family. First degree relatives include the mother/father, brothers/sisters, and children. Second degree relatives include grandparents, aunts/uncles, nieces, nephews, and grandchildren.

Cousins, who are third degree relatives, help complete the full picture. Ethnicity and race are also important because of the higher prevalence of certain gene changes in specific populations. A family history questionnaire is usually distributed and completed prior to an individual's office visit. Completing a family history questionnaire gives a person the opportunity to contact relatives and gather more detailed information before speaking with a genetic counselor who will analyze the family history. 
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Can several family members have cancer without it being hereditary? 
Non-hereditary or non-genetic factors may also increase a person's risk to develop cancer. For example, cancer may occur in a family at a higher than expected rate due to hormonal or reproductive factors, lifestyle, or environmental exposures, such as smoking cigarettes. 
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Is gene testing available for certain types of cancer? Who are candidates for gene testing? 
Over the past decade, research advances have led to the identification of many genes responsible for hereditary cancer syndromes. Currently, testing is available for breast, ovarian, colon, and medullary cancers, retinoblastoma, and other more rare cancer types. In many cases, gene testing involves a simple blood test after a person receives genetic counseling. Although genetic testing is available for a number of hereditary cancers, it is not practical or appropriate to screen everyone, since only 5 to 10 percent of all cancers is due to an inherited risk. 
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Who should have genetic testing for hereditary cancer? 
Analysis of a person's medical and family history is used to determine whether genetic counseling and genetic testing are necessary. Genetic testing may be considered in the following situation(s): 

  1. When an individual has a reasonable likelihood of carrying a cancer predisposing gene change.
  2. When a genetic test is available that can be adequately interpreted. 
  3. When results of testing will influence medical management. 
  4. When the information revealed from testing will be meaningful and empowering to the person.

Genetic testing is always voluntary and is a decision to be made only after the risks, benefits and limitations have been presented by a trained genetic counselor.  back to top 

What are the benefits of genetic testing for hereditary cancers? 
For people in higher risk families with a known change in a cancer susceptibility gene, a negative test can provide a sense of relief. Additionally, unaffected family members of patients with identified gene changes who test negative can be spared the need for intensive cancer screening and intervention. 

A positive test can help individuals make decisions about follow-up care. Some individuals may choose to have surgeries such as a prophylactic mastectomy or oophorectomy. These surgeries can reduce the risk of developing cancer in a particular organ. Additionally, patients may feel empowered by detecting cancer early through intensified screening or reducing their risk for cancer by altering their lifestyle. Results of gene testing in some families may also guide family

Genetic testing involves complex issues that should be discussed with the individual considering testing. For this reason and others, genetic counseling is an important component of the process -- both before testing is considered, and after a test is ordered. 
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Is genetic testing covered by insurance? 
Some genetic tests for well-defined hereditary cancers where a positive or negative result will change medical care, are considered part of standard management. Other genetic tests for hereditary syndromes where medical benefit of identifying a mutation carrier is not yet established, are not considered standard medical practice. Recently, there has been a trend among the larger insurance companies to recognize the importance of testing and provide coverage for genetic counseling and testing. 

Genetic testing raises ethical, legal and social questions, and therefore some individuals do not want their health insurance company to know if they carry a cancer predisposing gene change. Some fear that the company may use this information to raise premiums or cancel coverage. The extent to which this type of discrimination may occur is unknown. Applicable federal and state laws are explained to individuals considering genetic testing by a genetic counselor. 
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