About Clinical Genetics

Genetics and Cancer

  • One out of three Americans will develop cancer sometime in their lifetime.
  • The cancer process usually begins when one cell grows and multiplies uncontrollably, forming a tumor that can spread to different parts of the body. This is a several step process and may take many years.
  • Generally, the risk of developing cancer increases as we get older. In fact, most cases of cancer are diagnosed in people over age 55. However, a family history of cancer can increase the risk to develop certain types of cancer, even before age 50.
  • Individuals at average risk for cancer (no personal or family history of medical conditions, exposures and/or cancers that would increase risk) should follow the recommended cancer screening guidelines for the general population.
  • Individuals at increased risk for cancer (those at known or suspected increased risk due to personal or family history of certain medical conditions, exposures and/or cancers) may need to begin screening at an earlier age.
  • All cancer is genetic, but not all cancer is inherited.

What do the terms GENETIC and INHERITED mean?

  • Genetic means caused by a change in the genes, which are the units of instruction in most cells of our body that control our normal growth and development.
  • Inherited or inheritance refers to characteristics or qualities we receive from our parents as a result of their passing on genes contained in their egg or sperm cells.
  • Most cases of cancer (about 90 percent) occur by chance, starting in one cell in a specific site (organ) of the body. This cannot be passed on to the next generation (our children).
  • Some individualsĀ are at increased risk for developing cancer because they inherited a gene change from either of their parents that makes them more susceptible to certain cancer(s). This hereditary risk accounts for only 5-10 percentĀ of all cancers. However, even with inherited risk for cancer, other genetic factors and environmental (not inherited) factors play a role in whether or not cancer will actually develop.