What is fluorouracil?

Old anti cancer drug: Fluorouracil, also called 5-fluorouracil or 5FU, is a drug that's been used to treat cancer for many decades. It is commonly used to treat colon cancer, but has activity in many other cancers. It's given by injection, and works better if given as a prolonged infusion rather than a bolus injection. Capecitabine is a related drug, taken orally, which is converted into 5FU in the body.