Chemotherapy literally refers to the treatment of certain diseases using specific chemicals that are destructive to malignant cells or to the causative agent of a disease such as a bacteria or virus. Therefore, the treatment can be broadly divided into two categories - cancer chemotherapy and antimicrobial chemotherapy.
The first antimicrobial chemotherapy was developed by Sir Paul Ehrlich in 1909 when he found that an arsenic compound called arsphenamine could be used to treat syphilis infection. The antibacterial properties of the sulphonamides were discovered by the German pathologist Gerhard Domagk who received the Nobel Prize in Medicine in 1939 for discovering the first effective drug against bacterial infections. Unlike penicillin for example, the sulphonamides are synthetic antimicrobial agents rather than substances that are derived from microorganisms such as fungi.
Cancer chemotherapy involves the use of one or more cytotoxic agents to treat cancer. The term "cytotoxic" means toxic to cells and the general premise of chemotherapy is the toxic destruction of rapidly dividing cells.
However, chemotherapy also kills healthy cells that divide rapidly under normal circumstances, such as those in the bone marrow where red blood cells, white blood cells and platelets are produced. Rapid cell division also occurs in the hair follicles and the digestive tract. Therefore, chemotherapy typically causes side effects such as anemia, infection and a tendency to bleed easily due lowered levels of red blood cells, white blood cells and platelets.
Destruction of the gut lining causes nausea, vomiting and diarrhea and damaged hair follicles leads to hair loss.
Chemotherapy is usually given in cycles, as a series of treatment sessions, followed by a period of rest.
Other uses of chemotherapy
Apart from cancers and infections, chemotherapy may also be used in certain other conditions including autoimmune disease, multiple sclerosis, lupus, rheumatoid arthritis and dermatomyositis.