Rheumatoid arthritis, treatment with corticosteroids and risk of malignant lymphomas: results from a case-control study

Background Benefits and risks of corticosteroid treatment in rheumatoid arthritis (RA) are debated. Patients with RA are at increased risk of malignant lymphomas. In a large case-control study of risk factors for lymphoma in RA, it was recently reported that steroid treatment was associated with decreased lymphoma risk. Objective To further assess the nature of the association between steroid treatment in RA and the risk of lymphoma. Methods In a cohort of 74 651 patients with RA, 378 patients with lymphoma and 378 matched RA controls were identified, and information on inflammatory activity and different aspects of steroid treatment (duration, therapeutic strategy and mode of administration) abstracted from their medical records. Lymphomas were reclassified (WHO classification) and examined for Epstein-Barr virus. Relative risks were assessed as adjusted odds ratios (ORs) through conditional logistic regression. Results A total duration of oral steroid treatment of <2 years was not associated with lymphoma risk (OR=0.87; 95% CI 0.51 to 1.5), whereas total treatment >2 years was associated with a lower lymphoma risk (OR=0.43; 95% CI 0.26 to 0.72). RA duration at the initiation of oral steroids did not affect lymphoma risk. Intra-articular steroids were associated with a reduced lymphoma risk, but only when used as swift flare treatment (OR=0.22; 95% CI 0.13 to 0.37). Analyses by lymphoma subtype showed a reduced risk of diffuse large B-cell lymphoma (crude OR=0.59; 95% CI 0.37 to 0.94). Conclusion In this RA population, use of steroids was associated with reduced lymphoma risk. Whether this association is a generic effect of steroids or specific to the studied population remains unknown.