Severe Arthritis Linked to Cancer Risk
But Rheumatoid Arthritis Treatments Don't Raise Risk, Study Shows
Feb. 27, 2006 - Rheumatoid arthritis patients with the most severe disease
are roughly 70 times more likely to develop lymphoma, a type of cancer, than
patients with mild disease, according to new research from Sweden.
The findings provide some of the best evidence yet linking the elevated
lymphoma risk among rheumatoid arthritis (RA) patients to the disease itself
and not the drugs used to treat it.
In fact, researchers suggest that the drugs Enbrel, Remicade, and Humira and
other new and old treatments for RA may actually reduce the chances of
developing lymphoma in high-risk patients by reducing inflammation.
"Conventional medical treatment to suppress and alleviate disease
activity is not by itself a risk factor for lymphoma," they write in the
March 2006 issue of Arthritis and Rheumatism.
About 2 million Americans have rheumatoid arthritis, a progressive disease
characterized by inflammation of the lining of the joints. The joint damage
that occurs over time can lead to chronic pain and disability.
People with rheumatoid arthritis are roughly twice as likely as those
without the disease to develop lymphoma, which is a broad term for a variety of
cancers of the lymphatic system.
Researcher Eva Baecklund, MD, PhD, and colleagues drew from a Swedish
national registry that included nearly 75,000 RA patients to conduct the
The researchers compared 378 RA patients diagnosed with lymphoma between
1964 and 1995 to an equal number of RA patients without lymphoma matched for
age, time of RA diagnosis, and place of residence.
Patients with moderate inflammation were eight times more likely to develop
lymphoma than patients with mild rheumatoid arthritis. Those with high RA
activity were 70 times more likely to develop lymphoma.
"The association between lymphoma risk and very high and/or longstanding
disease activity indicates that most patients with RA will never have any
clinically relevant increased lymphoma risk," Baecklund and colleagues
More than 70% of the RA patients included in the study had been treated with
disease-modifying antirheumatic drugs (DMARDs) -- including the drug
methotrexate, which was recently linked to an increased risk of Epstein-Barr
virus-positive lymphomas in a French study.
But Baecklund and colleagues found no evidence linking methotrexate or any
other DMARD to an increase in cancer risk. The same was true for nonsteroidal
anti-inflammatory drugs and steroids.
Rheumatologist Daniel Solomon, MD, of Boston's Brigham and Women's Hospital,
tells WebMD that there has been particular concern that some newer DMARDs may
The research by Baecklund and colleagues has been reassuring, he says, but
there are still unanswered questions that will be difficult to answer.
"There is a lot of interest in whether [lymphoma risk] is drug-related
or disease-related," he says. "It is the $64,000 question and we don't
yet have the answer. It will be a hard issue to disentangle."