GLASGOW, SCOTLAND — Data from a large cohort of patients with rheumatoid arthritis receiving anti-tumor necrosis factor-α therapy has determined that those with a history of malignancy are at heightened risk for additional cancers, and therefore such treatment should be used “with extreme caution” in these patients, according to Kath D. Watson, Ph.D.
Because anti-tumor necrosis factor (anti-TNF) plays an important role in the immune system's tumor surveillance, its blockade could potentially increase the risk of cancer, Dr. Watson said at the annual meeting of the British Society for Rheumatology. Although there have been reports of malignancies such as lymphoma associated with biologic response modifiers, the data thus far have been insufficient to precisely quantify the degree of risk—or to sort out risks deriving from treatment from those inherent in the disease process.
Analysis of data from the British Society for Rheumatology biologics registry is now beginning to clarify these concerns, as cancer incidence among 9,999 first-exposure anti-TNF-treated patients was compared with that of 1,877 biologic-naive rheumatoid arthritis patients taking traditional disease-modifying antirheumatic drugs (DMARDs), according to Dr. Watson of the Arthritis Research Campaign's epidemiology unit, University of Manchester, England.
Participants were followed from the date of their registration through September 2005, and reports on cancer cases were obtained from the Office for National Statistics or from 6-monthly physician questionnaires. Incidence rate ratios were adjusted for age, gender, disease severity, and smoking history.
The incidence of new malignancies among the anti-TNF-treated patients overall was not elevated, compared with that of the DMARD-treated group, with a relative risk of 0.7, Dr. Watson said.
But patients treated with biologics who had previous malignancies had an increased risk of developing a further malignancy after commencing therapy, with an incidence rate ratio of 2.5. This increased risk was higher than that for DMARD-treated patients who had had previous cancers. (See box.)
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