Chemotherapy refers to treatment with particular drugs. These drugs may be used to kill or slow the reproduction of rapidly growing cancer cells. But there are also other uses for chemotherapy.
In rheumatology, chemotherapy is designed to alter the abnormal behavior of cells. The doses of medication used for rheumatic or autoimmune conditions are lower than the doses used for cancer treatment.
There is no specific test to diagnose ankylosing spondylitis, but imaging by X-ray and MRI may show evidence of inflammation of the sacroiliac joint between the sacrum (the triangular bone at the lowest part of the back) and the ilium (the bone felt on the upper part of the hip). Some symptoms may include:
Inflammatory back pain (gradual in onset, lasting over three months, with stiffness and pain that is worse in the morning and improved with movement)
Reduced mobility of the spine
How Does Chemotherapy 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 in which a person's own tissues or organs are mistakenly attacked by the body's immune system.
Chemotherapy slows cell reproduction and decreases certain products made by these cells. Therefore it 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 Doctors Use?
Although there are many chemotherapy drugs, only three are widely used in treating rheumatic diseases today. These are:
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 people can take methotrexate by mouth in a single, weekly dose. Some patients prefer to take it as an injection once a week.
Azathioprine has been used for many years as an immunosuppressive drug to prevent rejection in patients receiving kidney transplants. It is also used to suppress the abnormal immune response in some patients with vasculitis, systemic lupus erythematosus, rheumatoid arthritis, and vasculitis. Azathioprine has been linked to lymphoma, a cancer of the lymph nodes.
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 lupus and some forms of vasculitis.
Cyclophosphamide directly attacks rapidly reproducing cells such as those in the immune system. Resting cells, that are not multiplying, can be affected if there is enough drug present. It is taken either by mouth or by injection.