Treatment for cancer or infections with synthetically produced chemical substances. The term is commonly used, however, to refer to cancer treatment. The substances used in chemotherapy are designed to impair the growth or multiplication of the cells that cause the disease, or as far as possible eradicate them. In the treatment of malignant diseases, numerous weak points in the cycles during which tumor cells frequently and rapidly divide are susceptible to attack. Cancer medicines that target these points and impair cell division are also known as cytostatics. (See “conditioning”).