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”).