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Get the Facts: Genetics and Family History

Focused on Health - December 2008

By Rachel Winters

This year, an estimated 1.4 million Americans will be diagnosed with cancer. Seventy-seven percent of these cancers will occur in people over the age of 55. For men, the lifetime risk of cancer is one in two. For women, the lifetime risk of cancer is one in three (American Cancer Society).

Cancer has its roots in our genes, and genes can be altered or mutated in several ways. It is these alterations that can lead to cancer. Gene mutations can be either inherited from a parent or, more commonly, they are acquired. Even though all cancers are “genetic” because they have to do with our genes, just a small portion – about 5 or 10% – are actually inherited. Because most cases of cancer occur in people with no family history of the disease, cancer is not considered an inherited disease (National Cancer Institute).

Human cells contain two sets of chromosomes, one inherited from the mother and one from the father, so each child in the family has a 50% chance of inheriting hereditary cancer. Individuals who inherit one of these gene changes will have a higher likelihood of developing cancer within their lifetime and at a younger age. An accurate genetic test can tell if a mutation is present, but finding one does not guarantee that cancer will develop.

Common cancers associated with family history are:

  • Breast cancer
  • Colorectal cancer
  • Ovarian cancer
  • Prostate cancer
  • Endometrial cancer

If you think you might be at risk for an inherited cancer, speak with your health care provider about your family history. It is possible that genetic testing (pdf) might be right for you.

For those individuals who have been referred for genetic counseling or testing, it is important to know that legislation on the state and national levels protects individuals in group health plans from discrimination based on genetic testing results. A new Genetic Information Nondiscrimination Act will go into effect in November 2009.

Remember, however, that about one-third of cancers are associated with diet and exercise and that the most common risk factors for cancer are:

Reduce your risks of developing cancer no matter what your genetic risks might be by making healthy lifestyle choices.

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© 2014 The University of Texas MD Anderson Cancer Center