NCI Dictionary of Cancer Terms

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The NCI Dictionary of Cancer Terms features 7,811 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.

lead compound
(leed KOM-pownd)
In medicine, a chemical compound that shows promise as a treatment for a disease and may lead to the development of a new drug. Thousands of compounds are tested in the laboratory to find a lead (“leading”) compound that may act on specific genes or proteins involved in a disease. Once a lead compound has been found, the chemical structure is used as a starting point to make a drug that has the most benefits and the least harms. Finding a lead compound is the first step in making a new drug to treat a disease.