NCI Dictionary of Cancer Terms

The NCI Dictionary of Cancer Terms features 8,492 terms related to cancer and medicine.

We offer a widget that you can add to your website to let users look up cancer-related terms. Get NCI’s Dictionary of Cancer Terms Widget.

A change in the chemical structure of DNA that does not change the DNA coding sequence. Epimutations occur in the body when chemical groups called methyl groups are added to or removed from DNA or when changes are made to proteins called histones that bind to the DNA in chromosomes. These changes may occur with age and exposure to environmental factors, such as diet, exercise, drugs, and chemicals. They can affect a person’s risk of disease and may be passed from parent to child. Also called epigenetic alteration and epigenetic variant.