Your DNA is the material in your cells that is the building blocks for your genes. Genes are the instructions that tell each cell how to grow, develop, and work. Some things your genes control are:

• How fast each cell grows

• How often it divides to make new cells

• How long it lives

The genes in each cell are arranged in structures called chromosomes.

Genetic testing helps estimate your chance of developing cancer in your lifetime. It does this by searching for specific changes in your genes, chromosomes, or proteins. These changes are called mutations.

Genetic tests are available for some types of cancer. These include:

• Breast cancer

• Ovarian cancer

• Colon cancer

If you have a higher risk of developing cancer or of cancer coming back, there may be medication available to help lower that risk. This is called "chemoprevention."

Cancer begins when healthy cells change and grow out of control. The process of a healthy cell becoming cancerous often takes years. Many genetic and lifestyle factors, such as smoking, may affect this process. Cancer chemoprevention uses drugs, vitamins, and other substances to help keep cancer from developing or keep cancer from coming back.