As they divide, replicas are produced. Cancer cells, on the other hand, grow out of control. There is no apparent pattern at all. When in contact with a normal cell, the cancer cell takes over and copies itself many times over. In this way, the body becomes overburdened with cancer cells.
Chemotherapy destroys cancer cells with drugs.
Chemotherapy drugs interfere with the cancer cells' ability to grow or multiply. Different groups of drugs act on cells in different ways. Identification of the type of disease is important because certain chemotherapies work best for certain diseases. For example, a patient treated for acute myelogenous leukemia is treated with different agents than one treated with Hodgkin's disease. Even patients diagnosed with the same disease may be treated with different agents, depending on what is known to be most effective for the particular circumstances.