A series of anti-cancer drug treatments. Chemotherapy is normally given in cycles – where the drugs are given and then there is a break to allow the body to recover before the drugs are given again. A course of treatment is made up of a number of cycles of treatment. So, a course of treatment may take anything from a few weeks to several months. Rarely, in some types of leukaemia, a course of treatment may take 2 to 3 years.