THURSDAY, Oct. 29 (HealthDay News) -- Treatment with tumor necrosis factor (TNF) blockers doesn't increase rheumatoid arthritis patients' risk of cancer, new research has found.

TNF is a substance secreted by immune cells that regulates the immune system and plays a role in inflammation. TNF blockers are immunosuppressants that reduce inflammation in people with rheumatoid arthritis, but concerns have been raised that long-term use of the drugs may increase the risk of infections and cancer.

Swedish researchers analyzed data from 6,366 rheumatoid arthritis patients who started anti-TNF therapy with infliximab (Remicade), adalimumab (Humira) or etanercept (Enbrel) between January 1999 and July 2006. The study participants were compared with other groups of rheumatoid arthritis patients, including 61,160 not taking medications, 4,015 taking methotrexate (the gold standard of treatment) and 4,105 taking combinations of disease-modifying anti-rheumatic drugs (other than TNF blockers).

According to the study authors, 240 first cancers were diagnosed during follow-up among patients who had no history of cancer when they began anti-TNF treatment. Compared to rheumatoid arthritis patients who didn't take anti-TNF drugs or those with no history of cancer, the relative cancer risk of anti-TNF therapy was 1.00 and remained unchanged for those taking immunosuppressant drugs for up to six years, the researchers found.

"Our research indicates the overall cancer risk is the same for rheumatoid arthritis patients on immunosuppressant therapies and those not taking medications for the disease," confirmed team leader Dr. Johan Askling, of the Karolinska University Hospital in Stockholm, in a news release. However, "given several uncertainties, continued vigilance remains prudent."

The study is published in the November issue of Arthritis & Rheumatism.

More information

The American Academy of Family Physicians has more about rheumatoid arthritis.