Systematic review with meta-analysis: comparative risk of lymphoma with anti-tumour necrosis factor agents and/or thiopurines in patients with inflammatory bowel disease.

BACKGROUND The risk of lymphoma in patients with inflammatory bowel disease (IBD) treated with anti-TNF agents remains unclear. AIM To assess the comparative risk of lymphoma with anti-TNF agents and/or thiopurines in IBD METHODS: We searched PubMed, EMBASE and Cochrane Library to identify studies that evaluated lymphoproliferative disorders associated with anti-TNF agents with or without thiopurines. The risk of lymphoma was assessed through four comparator groups: combination therapy (anti-TNF plus thiopurine), anti-TNF monotherapy, thiopurine monotherapy and control group. Pooled incidence rate ratios (IRR) were estimated through Poisson-normal models. RESULTS Four observational studies comprising 261 689 patients were included. As compared with patients unexposed to anti-TNF and thiopurines, those exposed to anti-TNF monotherapy, thiopurine monotherapy or combination therapy had pooled IRR (per 1000 patient-years) of lymphoma of 1.52 (95% CI: 1.06-2.19; P = 0.023), 2.23 (95% CI: 1.79-2.79; P < 0.001) and 3.71 (95% CI: 2.30-6.00; P ≤ 0.01), respectively. The risk of lymphoma associated with combination therapy was higher than with thiopurines or anti-TNF alone with pooled IRR of 1.70 (95% CI: 1.03-2.81; P = 0.039) and 2.49 (95% CI: 1.39-4.47; P = 0.002), respectively. The risk did not differ between anti-TNF monotherapy and thiopurine monotherapy with pooled IRR of 0.72 (95% CI: 0.48-1.07; P = 0.107). All observational studies were of high quality according to the Newcastle-Ottawa scale. CONCLUSIONS There is an increased risk of lymphoma in IBD patients treated with anti-TNF agents, either alone or when combined with thiopurines.