The finding -- from 13,001 rheumatoid arthritis patients who twice a year completed detailed health questionnaires -- underscores recent evidence that higher doses of new arthritis drugs increase patients' cancer risk.
The new study contradicts earlier findings that the new drugs raise patients' risk of solid tumors. But it supports earlier findings linking the new "TNF blocker" drugs to skin cancers, including potentially deadly melanomas.
Even so, the small risk does not outweigh the benefit for patients who truly need the new drugs, says study investigator Frederick Wolfe, MD, director of the National Data Bank for Rheumatic Diseases.
The findings appear in the September issue of the journal Arthritis & Rheumatism.
Rheumatoid Arthritis Drugs
Rheumatoid arthritis is an immune disease. So-called "TNF blocker" drugs interfere with an immune-system signal called tumor necrosis factor alpha, or TNF-alpha. That can be a huge benefit to people crippled by rheumatoid arthritis. But it can also expose patients to risks of serious infections and cancers.
Three of these drugs are approved in the U.S.: Remicade, Enbrel, and Humira. The Wolfe study, conducted from 1998 through 2005, included very few patients on Humira. Most of the study patients taking TNF blockers in this study used Remicade.
A 2006 analysis of TNF-blocker clinical trials focused on Remicade and Humira (an update including Enbrel data is in the works). One of that study's investigators, Mayo Clinic rheumatologist Tim Bongartz, MD -- not a participant in the Wolfe study -- says Wolfe's findings are similar to those of Swedish investigators who also found a link between skin cancer and TNF blockers.
"Three major clinical trials, in their malignancy data, all have some indication there is a problem with skin cancer with these drugs," Bongartz tells WebMD. "This has huge implications in how we examine these patients and how we advise these patients."
Bongartz suggests doctors should do regular, thorough, whole-body skin examinations for every patient taking TNF blockers.
Wolfe is less concerned.
"If there is a real message in these studies, it is that the overall risk of cancer is small in rheumatoid arthritis patients," he says. "The overall effect is to say things are much the same as they have been over the last several decades. That is reassuring with these new drugs. ... I don't think people should be concerned. It may be these drugs turn out to be safe. It looks as though they are, and I am not particularly worried."
Bongartz says the real cancer risk of TNF blockers remains an open question. Apart from the question of cancer, Bongartz is certain that these drugs do increase a person's risk of a serious infection. But even this, he says, is no reason for patients who need the drugs to stop taking them.
"It just tells doctors something about how to manage these patients," Bongartz says. "If someone turns up in the emergency room with vague symptoms, if that patient is taking a TNF blocker, the doctors should be more alert."
A recent two-year study found the TNF blocker Enbrel to be safe in the long-term treatment of psoriasis.