Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of
cancer treatment that uses one or more anti-cancer
drugs (chemotherapeutic agents) as part of a standardized
chemotherapy regimen.
Chemotherapy may be given with a curative intent (which almost always involves combinations of drugs), or it may aim to prolong life or to reduce symptoms (palliative chemotherapy).
Chemotherapy is one of the major categories of the medical discipline specifically devoted to pharmacotherapy for cancer, which is called medical oncology.The term
chemotherapy has come to connote non-specific usage of intracellular poisons to inhibit mitosis, cell division. The connotation excludes more selective agents that block extracellular signals (signal transduction). The development of therapies with specific molecular or genetic targets, which inhibit growth-promoting signals from classic endocrine
hormones (primarily
estrogens for breast
cancer and androgens for prostate cancer) are now called hormonal therapies. By contrast, other inhibitions of growth-signals like those associated with receptor tyrosine kinases are referred to as targeted therapy.Importantly, the use of
drugs (whether chemotherapy, hormonal therapy or targeted therapy) constitutes systemic therapy for
cancer in that they are introduced into the blood stream and are therefore in principle able to address
cancer at any anatomic location in the body. Systemic therapy is often used in conjunction with other modalities that constitute local therapy (i.e. treatments whose efficacy is confined to the anatomic area where they are applied) for
cancer such as radiation therapy, surgery or hyperthermia therapy.Traditional chemotherapeutic agents are cytotoxic by means of interfering with
cell division (mitosis) but
cancer cells vary widely in their susceptibility to these agents. To a large extent,
chemotherapy can be thought of as a way to damage or
stress cells, which may then lead to cell death if
apoptosis is initiated. Many of the side effects of
chemotherapy can be traced to damage to normal
cells that divide rapidly and are thus sensitive to anti-mitotic drugs:
cells in the bone marrow, digestive tract and hair follicles. This results in the most common side-effects of chemotherapy: myelosuppression (decreased production of blood cells, hence also immunosuppression), mucositis (inflammation of the lining of the digestive tract), and alopecia (hair loss). Because of the effect on immune
cells (especially lymphocytes),
chemotherapy drugs often find use in a host of diseases that result from harmful overactivity of the
immune system against self (so-called autoimmunity). These include rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis,
vasculitis and many others
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