Background: Lymphomas comprise a heterogeneous group of malignant diseases with highly variableprognosis. Rheumatoid arthritis (RA) is associated with a 2-fold increased risk of both Hodgkin and non-Hodgkin lymphoma (HL; NHL). It is unknown whether treatment with biologic disease modifying antirheumatic drugs (bDMARDs) affects the risk of specific lymphoma subtypes.
Methods: Patients never exposed to (bio-naïve) or ever treated with bDMARDs from 12 European biologics registers were followed prospectively for the occurrence of first ever histologically confirmed lymphoma. Patients were considered exposed to a bDMARD after having received the first dose. Lymphomas were attributed to the most recently received bDMARD.
Results: Among 124,997 patients (mean age 59 years; 73.7% female), 533 lymphomas were reported. Of these, 9.5% were HL, 83.8% B-cell NHL, and 6.8% T-cell NHL. No cases of hepatosplenic T-cell lymphoma were observed. Diffuse large B-cell lymphoma (DLBCL) was the most frequent B-cell NHL subtype (55.8% of all B-cell NHLs). The subtype distributions were similar between bio-naïve patients and those treated with TNF inhibitors (TNFi). For other bDMARDs, the numbers of cases were too small to draw any conclusions. RA patients developed more DLBCLs and less chronic lymphocytic leukaemia compared to the general population.
Conclusion: This large collaborative analysis of European registries has successfully collated subtype information on 533 lymphomas. While the subtype distribution differs between RA and the general population, there was no evidence of any modification of the distribution of lymphoma subtypes in RA patients treated with TNFi compared to bio-naïve patients.