Chemotherapy is the administration of cancer-fighting medication (cytotoxic drugs) to destroy cancer cells. The drugs also affect healthy cells, causing side effects such as a feeling of nausea or increased risk of infection. Unlike cancer cells, these cells usually repair themselves. Most of the side effects improve once the treatment has concluded.

Chemotherapy may be administered as a main treatment or after other treatments to reduce the risk of the cancer recurring. It is sometimes used at the same time as radiotherapy. Chemotherapy is also given to control cancer that has spread and to relieve symptoms.

The type of chemotherapy will depend on several things, such as cancer type, the risk of the cancer coming back, or whether it has spread. Some people have tests performed during the treatment to check whether the cancer is responding to the chemotherapy.

Chemotherapy is usually given by injection or a "drip" into the vein or in tablet form. Sometimes it's given through other methods, such as into the spine or the bladder, depending on the type of cancer.