Study Eases Arthritis Drug Cancer Fears
Patients Taking TNF Inhibitors Had No Increase in Cancer Risk Over 6 Years
By
Salynn Boyles
WebMD Health News
Reviewed By
Louise Chang, MD
Oct. 29, 2009 -- Rheumatoid arthritis patients who
take the biologic drugs Remicade, Humira, and Enbrel do not appear to have an
increased risk for developing cancer in the first few years of use, researchers in
Sweden report.
The study is one of the largest and longest population-based investigations
ever into the cancer-causing potential of the drugs, known as tumor necrosis
factor (TNF) inhibitors.
TNF inhibitors were introduced a decade ago, and they represent a
significant advance in the treatment of patients with rheumatoid arthritis, Crohn's disease, and other diseases of the
immune system who do not respond to traditional treatments.
Concerns that the drugs may cause cancer emerged soon after they were
introduced, and the research examining the question has been mixed.
The new findings should reassure patients, but questions remain about the
short-term and long-term safety of TNF-blocking drugs, rheumatologist Eric
Matteson, MD, of Mayo Clinic in Rochester, Minn., tells WebMD.
The Swedish researchers found no difference in cancer risk among rheumatoid
arthritis patients who did and did not take the drugs over six years of
follow-up.
"We have to remain vigilant about the possibility that these drugs are
associated with an increased risk for cancer, and make sure we use the drugs
appropriately," he says. "They should only be used in the patients who really
require them."
TNF Blockers Safe?
Also known as TNF blockers, TNF inhibitors target the TNF-alpha protein that
is linked to inflammation and is overproduced in inflammatory diseases like
rheumatoid arthritis.
TNF-alpha is also a key player in helping the body fight cancer, leading
investigators to speculate that blocking it may promote cancer growth.
In the newly published study, researchers from Stockholm's Karolinska
University Hospital analyzed data from several Swedish health registries.
The analysis compared cancer incidence among patients who took either
Remicade, Humira, or Enbrel with patients who didn't.
It included 6,366 patients who started the TNF-blocking drugs between 1999
and 2006 and roughly 70,000 patients who were either not treated or took other
types of drugs.
The researchers found little difference in cancer incidence among patients
who did and did not take the TNF inhibitors. Patients who took the TNF-blocking
drugs for the full six years of the study had the same cancer risk as patients
who took no drugs at all for their rheumatoid arthritis.
There was a suggestion of an increase in cancer risk in patients taking the
biologic drugs in the first year of use, but not in the years that
followed.
"Our research indicates the overall cancer risk is the same for rheumatoid
arthritis patients on (immune-system suppressing) therapies and those not
taking medications for the disease," lead researcher Johan Askling, MD, and
colleagues write, adding that "given several remaining uncertainties, continued
vigilance remains prudent."
TNF Blockers and Skin Cancer
Two recent studies raised new fears that TNF-blocking drugs increase the
risk for nonmelanoma skin cancers.
In one, researchers reported that patients taking TNF inhibitors had a 34%
increased risk for nonmelanoma skin cancers, compared with patients taking
other disease-modifying antirheumatic drugs (DMARDs).
In another, the TNF-blocking drugs appeared to increase the risk for
developing nonmelanoma cancers by about 70%, compared to treatment with a
traditional DMARD.
Both were presented at the annual meeting of the American College of
Rheumatology in mid-October, where experts warned patients on the drugs to
check their bodies regularly for abnormal growths that can signal skin
cancer.
Given concerns about the potential risk for both infection and cancer in
patients who take TNF-blocking drugs, Matteson says it is important that
prescribing physicians use them only in patients who have few other
options.
He tells WebMD "the jury is still out" on whether they are being over
prescribed.
"The majority of patients with rheumatoid arthritis do just as well with
non-biologic treatments," he says.
SOURCES: Askling, J. Arthritis & Rheumatism, November 2009; vol 60: pp 3180-3189.
Eric Matteson, MD, rheumatologist, professor of medicine, Mayo Clinic, Rochester, Minn.
News release, Wiley-Blackwell.
FDA: "Q&A - TNF Blockers."
WebMD Medical Reference: "Biologics for Rheumatoid Arthritis Treatment."
WebMD Health News: "Medications for RA Linked to Skin Cancer."
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