Does Rheumatoid Arthritis Treatment Increase the Risk of Cancer?

Rheumatoid arthritis (RA) is the most common inflammatory form of arthritis, affecting more than 2 million Americans. It is a chronic, systemic, autoimmune disease which has no known cure, but which is capable of being put into remission.

A major evolution in therapy has occurred in the last fifteen years with the advent of what are known as biologic therapies.

These treatments are designed to act as laser-guided bullets, using proteins to knock out or intercept the abnormal messengers produced by inflammatory cells that cause rheumatoid arthritis to exist.

The obvious question raised by both patients as well as rheumatologists is this: What are the risks associated with "toying" with the immune system?

The answers appear to be the following: there is an increased risk of opportunistic infection, indicating the need to warn patients about exposure to different bacteria and fungi. Tuberculosis is a particularly dangerous "bug" to keep patients away from. Regular testing for tuberculosis is recommended.

Immunologic side effects such as neurologic disorders are also a potential threat. A multiple-sclerosis-like disorder has been seen in some patients.

Nonetheless, biologics, so far, seem to have an acceptable risk benefit ratio.

One question that has been posed by many is... "What about an increased risk for cancer?"

A recent study sheds some sobering light on this... but not in the way one might think. The conclusions reached by a study looking at data from the British Society for Rheumatology Biologics Register showed a 50 per cent increase in the risk of getting cancer in RA patients not treated with biologic therapy!

There has been a well-established link between RA and non-Hodgkins lymphoma. However, the Registry data indicates the risk for RA and contracting cancer is increased about 50 per cent. The population assessed was patients with the disease who were being treated with methotrexate alone. The study included 3,727 patients enrolled in the registry between 2002 and 2008.

Among the 148 malignancies, there were melanoma, lung cancer, breast cancer, and colorectal cancer. In addition, there were 20 patients who developed either non-Hodgkins lymphoma or Hodgkin's disease.

Another smaller British study looked at the risk of cancer in patients treated with anti-TNF therapies. What they found were numbers similar to patients not treated with biologics. There was an increased risk of lymphoma and an increased risk of skin cancers in general. What was different was that in this group, there was also an increased risk of malignant melanoma. This latter was the major differentiating feature between the two groups.

So bottom line: It appears that anti-TNF therapy for rheumatoid arthritis carries the same risk for cancer as does the underlying disease. One exception is the increased risk of malignant melanoma.