5. Chemotherapy is a course of treatment to address cancer based on the injection of anti-cancer drugs into a vein or through its administration by ingestion. The chemotherapy drugs enter the bloodstream and travel through the body in order to kill the cancerous cells. It is not usually the first course of treatment for patients with prostate cancer, but it may be an option for patients whose cancer has metastasized to other organs rather than just the prostate, or when hormone therapy is not working. (Read more about chemotherapy)