Chemotherapy in the beginning is not used in the treatment of patients. But used in World War I and II starting from mustard gas (Mastard gas).The doctors in modern foundthat mustard gas destroy the cell which have growth devide rapidly and they also note that cancer cells have a growth divide rapidly as well.So they experimented to give chemotherapy intoregimens veins With leukemia patients for the first time in 2483 which produce good result. After the trial. It's such a great awakening in the research and it Effectedin the treatment of cancer.