Meta‐analysis: Risk of lymphoma in patients with inflammatory bowel disease in population‐based cohort studies

SummaryBackgroundThere are inconsistencies in the results of the studies investigating the association between inflammatory bowel disease (IBD) and lymphoma.AimsThe aim of this study is to systematically appraise the risk of lymphoma development in patients with IBD.MethodsWe searched Embase, PubMed and Scopus from inception to 30 April 2024 to identify population‐based cohort studies that evaluated the risk of lymphoma in patients with IBD in comparison with those without IBD. We carried out random‐effects meta‐analyses and estimated pooled relative risks (RRs) with 95% confidence intervals (CIs).ResultsWe identified 23 eligible studies reporting 2078 lymphoma events in 656,731 patients with IBD. Patients with IBD had 30% higher odds of lymphoma (RR = 1.30 [95% CI: 1.21–1.40]). The risk of developing both Hodgkin's lymphoma (nine studies, RR = 1.29 [95% CI: 1.06–1.53]) and non‐Hodgkin's lymphoma (16 studies, RR = 1.31 [95% CI: 1.20–1.42]) was increased in patients with IBD (p for interaction = 0.881). The increased risk of lymphoma was observed in both Crohn's disease (17 studies, RR = 1.54 [95% CI: 1.27–1.80]) and ulcerative colitis (20 studies, RR = 1.22 [95% CI: 1.09–1.35]) (p for interaction = 0.026). Meta‐regression demonstrated that mean age of patients, study year, mean study follow‐up duration, and percentages of immunomodulators and biologics use did not influence study outcome.ConclusionsThe risk of lymphoma is only modestly increased in patients with IBD, with Crohn's disease having a slightly higher risk than ulcerative colitis. In IBD, there appears to be no difference between the risks of Hodgkin's and non‐Hodgkin's lymphoma.