NCI Dictionary of Cancer Terms
The NCI Dictionary of Cancer Terms features 7,846 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.
- listen (FOH-toh-ak-TIH-vih-tee)
- The effect produced when certain substances are exposed to light. In cancer treatment, some drugs become active when exposed to light and are then able to kill tumor cells.