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Study Focuses On Cancer Risk
In Biologic Treatment For Rheumatoid Arthritis
01
Sept 2007
As
edited by Joint-Pain-Forum.com
The
relationship between rheumatoid arthritis (RA), an autoimmune disease
marked by chronic inflammation of the joints and tissue surrounding
vital organs, and the incidence of cancer is complicated. Epidemiologic
studies have generally demonstrated that blood, lung, and skin cancers
are increased among RA patients, while breast and colon cancers are
decreased. Whether these cancer rates are caused by the nature of RA or
by immunosuppressive drugs used to treat RA is an issue of ongoing
debate and investigation. Findings of various clinical trials and
observational studies conflict over the risk of malignancy related to
the use of tumor necrosis factor alpha (TNFa) blockers, a biologic
therapy shown effective at controlling the symptoms of RA in patients
who fail to respond to traditional disease-modifying antirheumatic
drugs (DMARDs).
To assess the risk of cancer among
biologic-treated RA patients, comprehensively and conclusively, two
research specialists, Frederick Wolfe, MD, University of Kansas School
of Medicine, and Kaleb Michaud, PhD, University of Nebraska Medical
Center, turned to two sweeping databases, the National Data Bank for
Rheumatic Diseases and the US National Cancer Institute SEER
(Surveillance, Epidemiology, and End-Results). Gathering and comparing
data from both, they studied the incidence of cancer in 13,001 RA
patients, over a total span of close to 49,000 years. Nearly half of
these patients, 49 percent, had a history of exposure to anti-TNFá
drugs. As Dr. Wolfe and Dr. Kaleb found, and report in the September
2007 issue of Arthritis & Rheumatism (http://www.interscience.wiley.com/journal/arthritis),
biologic treatment of RA increases a patient's risk of skin cancers,
including melanoma, but not any other specific cancers--not lung,
liver, brain, or bone cancers, not Hodgkin's or leukemia, not solid
tumors or lymphoma--and not of developing cancer in general.
----------------------------
Article
adapted by
www.Joint-Pain-Forum.com from original press release.
----------------------------
Among the study population, Dr. Wolfe
and Dr. Kaleb identified 623 cases of skin cancer and 537 cases of
other cancers. Then, they set out to determine the impact of biologic
drug use on cancer occurrence. As an estimate of the relative risk of
developing different types of cancer, the team calculated the odds
ratio for every cancer afflicting the subjects, performing conditional
logistic regression to reduce the effect of variations in treatment
duration. They also controlled for the variables of sex, smoking
history, education level, disease severity, and baseline use of
prednisone. In addition to assessing the risk of various cancers
associated with biologic treatment in general, Dr. Wolfe and Dr. Kaleb
extended the analyses to individual TNFá blockers, etanercept and
infliximab.
Collectively and individually,
anti-TNFá therapy was linked to an increased risk of skin cancers. The
odds ratio for developing melanoma was 2.3. Biologic use had no impact
on any other type of cancer. The overall risk for all malignancies was
1.0--a result substantially different from the overall risk of 3.3
noted in a meta-analysis of clinical trials of biologic treatment of
RA.
"Although our data do not show associations
between malignancy and biologic therapy, except for skin cancers, the
mean and median exposure to biologics was only 3.0 years," notes Dr.
Michaud. "It is possible that with increasing time of followup or of
exposure, the association between malignancy and biologic therapy would
become stronger. However, true associations are regularly seen within
this time frame."
Despite its potential
limitations, this study offers reassurance to RA patients who are
currently being treated with etanercept or infliximab, as well as to
those considering biologic therapy as a possible option.
Article:
"Biologic Treatment of Rheumatoid Arthritis and the Risk of Malignancy:
Analyses From a Large US Observational Study," Frederick Wolfe and
Kaleb Michaud, Arthritis & Rheumatism,
September 2007; (DOI: 10.1002/art.22864).
Source:
Amy Molnar
John Wiley & Sons, Inc.
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