Rheumatoid arthritis drugs may up lymphoma risk

Taking "TNF blockers," such as Remicade and Enbrel, to treat Rheumatoid Arthritis does not increase the overall cancer risk, but the drugs may heighten the risk of lymphoma, according to a new report.

Still, because only a few patients in the study developed lymphoma, further research is needed to confirm these findings.

Previous reports have linked rheumatoid arthritis with an elevated risk of lymphoma, a cancer of the body's lymph node system.

Data from clinical trials has not supported an association with TNF blocker use, but to investigate this subject further, Dr. P. Geborek, from Lund University Hospital in Sweden, and colleagues analyzed data from 757 patients in southern Sweden who were treated with TNF blockers. A comparison group consisted of 800 patients who were treated with conventional antirheumatic drugs.

The researchers' findings appear in the Annals of the Rheumatic Diseases.

During follow-up, 16 tumors, including 5 lymphomas, were detected in the TNF blocker group. In the comparison group, 69 tumors, including 2 lymphomas, were identified.

Further analysis showed that TNF blocker-treated patients were nearly five times more likely to develop lymphoma, the investigators note.

Based on the cancer rates expected in southern Sweden, there was a rise in overall tumor risk in the comparison group, mostly due to an increase in smoking-related cancers. By contrast, TNF blocker-treated patients showed no increase in overall cancer risk.

The study is "welcome as it is the first direct attempt to investigate the relationship between disease severity, use of (TNF blockers), and risk of lymphoma in patients with Rheumatoid Arthritis," Dr. J. P. Franklin and colleagues, from the Manchester University Medical School in the UK, note in a related editorial. Nonetheless, further research is needed before any firm conclusions can be reached, they add.

SOURCE: Annals of the Rheumatic Diseases, April 19, 2005