TNF and lymphoma: In this study, an increased risk of lymphoma was found in those patients exposed to these drugs, with a pooled incidence rate ratio (IRR) of 1.52 (95% CI: 1.06–2.19) for those patients exposed to anti-TNF monotherapy vs. patients unexposed to anti-TNF of thiopurines; IRR 2.23 (95% CI: 1.79–2.79) in patients exposed to thiopurines monotherapy vs. controls; and IRR 3.71 (95% CI: 2.30–6.00) for patients on combination therapy vs. controls.