NCI Dictionary of Cancer TermsThe NCI Dictionary of Cancer Terms features 8,531 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.- listen (DA-koh-jen) A drug used to treat myelodysplastic syndromes. It is also being studied in the treatment of other types of cancer. Dacogen stops cells from making DNA and may kill cancer cells. It is a type of antimetabolite. Also called decitabine.