The treatment with
drugs or
chemicals of any disease or illness is called chemotherapy. However, the term is most commonly used to describe this kind of treatment for cancer.
In
cancer patients,
chemotherapy is generally used when the disease is so widespread that it cannot be easily removed with surgery or treated with radiation therapy to the local site of the cancer. There are more than 100 anticancer drugs in use today, and while they are sometimes administered alone more often they are administered in combinations.
Several types of anticancer drugs are used in chemotherapy. Hormones, which are naturally produced by the body, or their chemical derivatives, are used for specific types of cancer. Breast cancer can be treated and possibly prevented by inhibitors of female sex hormones. Tamoxifen is a representative of this type of chemotherapy. Similarly, inhibitors of male sex
Hormones are often used to treat prostate cancer. Steroid hormones related to those from the adrenal cortex are often used to treat lymphomas (cancer of the lymphatic system) or leukemia (cancer of the bone marrow).
Antimetabolites were the first
agents used in chemotherapy, in the 1940s. These chemicals kill cells by blocking synthesis of
essential molecules, such as DNA or other metabolites that are essential for cellular function. Alkylating agents are potent chemicals that bind and block the normal function of DNA. These are effective at multiple stages of the cell cycle. Antibiotics, naturally produced by a variety of microorganisms, are toxic to cancer cells. Plant alkaloids such as vincristine and vinblastine kill cancer cells by attacking essential structural elements in cells.
Combination chemotherapy is regularly used because chemotherapeutic agents often act in a synergistic manner. Also, genetic resistance to chemotherapy develops less often using a combination of agents than when these agents are used alone. Combination chemotherapy, while somewhat toxic and with systemic side effects, is successful in curing most children and many adults with acute leukemia, Hodgkin disease, and testicular cancer. It can also cause remission in other forms of cancer.
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