Oct. 19, 2009 (Philadelphia) -- People who take immune-disease drugs called TNF blockers for rheumatoid arthritis should check their bodies regularly for abnormal growths that can signal skin cancer.
That's the advice of doctors after two new studies showed that patients treated with TNF blockers have higher rates of skin cancer than patients who take other disease-modifying anti-rheumatic drugs, or DMARDs.
TNF, however, also has a normal function in the body: fighting cancer. The FDA already requires that TNF-blocking drugs carry a boxed warning of an increased risk of cancer.
The new studies link the drugs to skin cancer in particular and quantify "what we already suspected," says Eric Ruderman, MD, a rheumatologist at Northwestern University who was not involved in the new studies.
Still, experts stress that the overall risk of developing skin cancer is low and that for most patients with rheumatoid arthritis, the benefits of TNF blockers outweigh the risks.
"Yes, the findings give us pause, but TNF blockers have helped many patients ravaged by rheumatoid arthritis to become ambulatory," says Johns Hopkins rheumatologist Allan Gelber, MD.
Gelber moderated a news conference to discuss the new studies at the annual meeting of the American College of Rheumatology.
TNF Blockers and Skin Cancer
For the first study, researchers at Washington University in St. Louis combed the medical records of nearly 17,000 people with rheumatoid arthritis treated at VA hospitals around the country. About 3,000 of them were treated with TNF blockers.
Compared with people treated with other DMARDs such as Rheumatrex or Arava, people taking TNF blockers were 34% more likely to develop nonmelanoma skin cancer. The drugs were also associated with a slightly higher risk of malignant melanoma.
The longer a person was on TNF blockers, the greater their risk of nonmelanoma skin cancer, says Prabha Ranganathan, MD, a rheumatologist at Washington University.
Men, older patients, and those who took steroids to control their disease were also at increased risk of developing nonmelanoma skin cancer.
"Older patients with rheumatoid arthritis on anti-TNF therapy need to be watched closely for the development of skin cancer, especially if they are male, have been on these treatments for a long time, and have a history of other cancers," she tells WebMD.
British Study on TNF Blockers
For the second study, British researchers reviewed a national registry that tracks the progress of people with rheumatoid arthritis.
Taking a TNF-blocking drug appeared to increase the risk of developing nonmelanoma basal or squamous cell skin cancers by about 70%, compared to treatment with a traditional DMARD, but the finding could have been due to chance.
Further analysis showed that not all TNF blockers posed an equal risk. In particular, Remicade was associated with a significant threefold increased risk of skin cancer compared with DMARD treatment.
"One possible reason may be that because people go to the hospital to get Remicade, which is given as an infusion, they're around health care providers more often and therefore it's more likely that their cancer would be found," says Kimme Hyrich, MD, senior lecturer in rheumatic disease epidemiology at the University of Manchester, England.
The bottom line: People on TNF blockers should be get regular skin exams and report any unusual changes, such as moles or new lesions, to their doctors immediately, she tells WebMD.
Also at the meeting, researchers reported that rheumatoid arthritis patients who are taking TNF blockers appear to be at increased risk of septic arthritis -- an infection of the joints.
"The risk about doubles when compared to patients receiving treatment with other disease-modifying drugs," says Deborah Symmons, MD, professor of rheumatology and musculoskeletal epidemiology at the University of Manchester, England.
The study involved 11,757 people with RA who were taking TNF blockers and 3,515 patients taking other DMARDs.
Symmons tells WebMD she attempted to adjust for other factors that raise the risk of infection -- including that patients on TNF-blocking medications tend to have more severe rheumatoid arthritis than patients treated with other drugs. "However, that still left us with a residual additional risk associated with anti-TNF agents."