The Public Health Code (article L.5111-1) defines a medicinal drug as a “substance or compound presented as possessing properties that can cure or prevent diseases in humans and animals, and as any substance or compound that can be used in humans and animals or that can be administered to them, in view to formulating a medical diagnosis or restoring, correcting or modifying their physiological functions through pharmacological, immunological or metabolic action”.

Drugs used to combat cancer mainly comprise cytostatics (chemotherapy) that destroy cells that divide rapidly, such as tumour cells, antihormones (hormonotherapy) which inhibit the hormones favouring certain cancers, and immunotherapy drugs that help the immune system to eliminate cancer cells. Drugs stemming from recent so-called targeted therapies combat the development of tumours, by acting specifically on certain proteins that participate in the multiplication of cancer cells and the formation of blood vessels that nourish them.