Arthritis Health Center
Understanding Arthritis: What is Chemotherapy?
In cancer treatment, chemotherapy refers to particular drugs used to kill or slow the reproduction of rapidly multiplying cells.
In rheumatology, chemotherapy is designed to decrease the abnormal behavior of cells, rather than kill cells. The doses of medication used for rheumatic or autoimmune conditions are lower than the doses used for cancer treatment.
How does chemotherapy help treat inflammatory and autoimmune diseases?
In many rheumatic diseases, inflammation causes damage to parts of the body, such as what happens to the joints in rheumatoid arthritis. In many cases, inflammation results from autoimmunity, a malfunction of the immune system where one's own tissues or organs are not recognized as such and are attacked by the body's immune system.
Chemotherapy slows cell reproduction and decreases certain products made by these cells, and therefore may help people with certain inflammatory and autoimmune diseases. Because of the suppressive effect of chemotherapy on autoimmunity, these drugs are sometimes called immunosuppressive drugs.
What chemotherapy drugs do rheumatologists use?
Although there are many chemotherapy drugs, only three have widespread use in treating rheumatic diseases today. These are:
- methotrexate (Rheumatrex)
- azathioprine (Imuran)
- cyclophosphamide (Cytoxan)
Methotrexate
Methotrexate is the chemotherapeutic drug most widely used by rheumatologists for two main reasons. It is effective in treating rheumatoid arthritis and certain other rheumatic diseases (especially polymyositis and certain types of vasculitis or inflammation of blood vessels), and it is relatively safe.
Most patients can take methotrexate by mouth in a single, weekly dose. Some patients prefer to take it as an injection once a week.
Azathioprine
Azathioprine has been used for many years as an immunosuppressive drug to prevent graft rejection in patients receiving kidney transplants. Usually taken in a single daily dose by mouth, it is also used to suppress the abnormal immune response in some patients with vasculitis, systemic lupus erythematosus, rheumatoid arthritis and vasculitis.
Cyclophosphamide
Cyclophosphamide is considerably more powerful and toxic than methotrexate and azathioprine. It is used to treat the most aggressive and dangerous rheumatic diseases, such as severe systemic lupus erythematosus and some forms of vasculitis.
Cyclophosphamide directly attacks the parts of the cell nucleus that contain the genes - the nucleic acids - interfering with the production of certain proteins. Although rapidly reproducing cells are more susceptible to this action than resting cells, any cell can be affected if there is enough drug present.
Cyclophosphamide is taken either by mouth or by injection.
What side effects do these drugs have?
Side effects of chemotherapeutic drugs are fairly common, even though the doses are typically lower than the doses used to treat cancer.
All of these drugs can suppress the formation of blood cells, resulting in the following:
- Anemia: low red blood cell count
- Leukopenia/Neutrapenia: low white blood cell count that may cause decreased resistance to infection
- Thrombocytopenia: low platelet count that may cause impaired blood clotting
WebMD Medical Reference provided in collaboration with the Cleveland Clinic
