The risk of cancer in patients with rheumatoid arthritis taking tumor necrosis factor antagonists: a nationwide cohort study

Introduction: The association between cancer and use of biologic therapy among rheumatoid arthritis (RA) patients remains controversial. We aimed to compare the relative risk of cancer development between RA patients taking tumor necrosis factor a (TNF alpha) antagonists and those taking nonbiologic disease-modifying anti-rheumatic drugs (nbDMARDs). Methods: We conducted a nationwide cohort study between 1997 and 2011 using the Taiwan National Health Insurance Research Database. The risk of newly diagnosed cancer was compared between patients starting TNF-alpha antagonists (biologics cohort) and matched subjects taking nbDMARDs only (nbDMARDs cohort). Cumulative incidences and hazard ratios (HR) were calculated after adjusting for competing mortality. Standardized incidence ratio (SIR) was calculated for cancer risk. Multivariate analyses were performed using Cox proportional hazards model. Results: We compared 4426 new users of TNF-alpha antagonists and 17704 users of nbDMARDs with similar baseline covariate characteristics. The incidence rates of cancer among biologics and nbDMARDs cohorts were 5.35 (95% confidence interval (CI) 4.23 to 6.46) and 7.41 (95% CI 6.75 to 8.07) per 1000 person-years, respectively. On modified Cox proportional hazards analysis, the risk of cancer was significantly reduced in subjects in biologics cohort (adjusted HR 0.63, 95% CI 0.49 to 0.80, P < .001), after adjusting for age, gender, disease duration, major co-morbidities, and prior use of DMARDs and corticosteroids. However, there was an increased risk for hematologic cancers in biologics cohort, yet without statistical significance. The effect of biologics was consistent across all multivariate stratified analyses and the association between biologics use and cancer risk was independent of dosage of concomitant nbDMARDs. Conclusion: These findings suggested that RA patients taking TNF-alpha antagonist are associated with a lower risk of cancer, but not for hematologic cancers, than RA patients taking nbDMARDs alone.