CHICAGO – Patients with rheumatoid arthritis on antitumor necrosis factor drugs have no greater risk of developing solid cancers than RA patients on disease-modifying antirheumatic drugs, according to an analysis of registry data on more than 15,000 patients tracked for up to 5 years.
Among the 15,262 patients in the RA registry, 91 of the 3,543 participants taking DMARDs (2.6%) and 295 among 11,719 participants taking anti-TNF drugs (2.5%) developed solid cancers.
"I think these results are very reassuring and follow on nicely from results of early clinical trials. Overall, the risk of solid cancer with anti-TNF therapy does not appear to be increased," lead author Dr. Kimme Hyrich said at the annual meeting of the American College of Rheumatology.
"Of course this represents therapy only up to 5 years, and we know that cancer in general can take many, many years to develop or become clinically apparent. Therefore we need to continue to follow these patients," Dr. Hyrich noted.
The study corroborates previous studies showing a minimal cancer risk associated with the use of anti-TNF agents, many of which have been used in the treatment of RA for more than 10 years. "When they were first available for widespread use, I think there was a continuing anxiety about whether or not an agent, which blocks occult tumor necrosis factor, would actually increase the risk of cancer in patients with rheumatoid arthritis," said Dr. Hyrich, who is senior lecturer and consultant in rheumatology at the University of Manchester (England).
Studies since have been limited primarily to meta-analyses of randomized controlled trials of anti-TNF drugs. These trials tend to be of limited duration, and the participating patients tend to be highly screened. The participants may not represent patients in typical practice, Dr. Hyrich said.
In 2001, the British Society for Rheumatology Biologics Register was established to track the progress of patients with severe rheumatoid arthritis and other rheumatic diseases who are taking anti-TNF therapy. The registry also tracks patients with moderate to severe RA who are being treated with nonbiologic DMARDs; these patients served as a control group in this analysis.
Cancer cases were also identified by reviewing patient records. The study data were linked with the U.K. National Health Service Information Center’s national cancer register. "This is a mandatory reporting cancer register where every confirmed cancer in the United Kingdom is recorded," she explained.
The analysis was limited to solid cancers, specifically excluding lymphoma, leukemia, and skin cancers. The researchers compared the risk out to 5 years’ follow-up for those receiving anti-TNF therapies with the risk for those receiving nonbiologic DMARD therapies.
Dr. Hyrich noted that there were differences between the two patient groups. In particular, more men were on DMARDs, and those on DMARDs were slightly older. "Both of these are recognized risk factors for cancer in general," he said. The results, however, were statistically adjusted to balance the risk between the two groups. The investigators found no significant differences between the groups after adjustment.
Dr. Hyrich reported having no relevant financial disclosures.