NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,847 terms related to cancer and medicine.

Browse the dictionary by selecting a letter of the alphabet or by entering a cancer-related word or phrase in the search box.

small-molecule drug
(… MAH-leh-kyool ...)
A substance that is able to enter cells easily because it has a low molecular weight. Once inside the cells, it can affect other molecules, such as proteins, and may cause cancer cells to die. This is different from drugs that have a large molecular weight, such as monoclonal antibodies, which are not able to get inside cells very easily. Many targeted therapies are small-molecule drugs or small molecule inhibitors.