Systematic review with meta‐analysis: thiopurines decrease the risk of colorectal neoplasia in patients with inflammatory bowel disease

Summary Background Patients with inflammatory bowel disease (IBD) have a high risk of developing colorectal neoplasia. Aim To investigate whether thiopurines can decrease the risk of developing colorectal neoplasia in patients with ulcerative colitis (UC) or Crohn's disease (CD). Methods We conducted a meta‐analysis of 24 observational studies involving 76,999 participants to evaluate the risks of developing colorectal neoplasia in IBD patients receiving thiopurine treatment. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) for the risks of colorectal neoplasia were calculated using a random‐effects model. Results The overall pooled estimate revealed a protective effect of thiopurine use on colorectal neoplasia in patients with IBD (OR = 0.63, 95% CI 0.46‐0.86). The effect was significant in UC patients (OR = 0.67, 95% CI 0.45‐0.98), but was not significant in CD patients (OR = 1.06, 95% CI 0.54‐2.09). Thiopurines exposure significantly decreased the risk of colorectal cancer (CRC) (OR = 0.65, 95% CI 0.45‐0.96) and advanced colorectal neoplasia (CRC and/or high‐grade dysplasia) (OR = 0.62, 95% CI 0.44‐0.89), but did not decrease the risk of dysplasia alone (OR = 0.90, 95% CI 0.37‐2.21). Tendencies towards the protective effect of thiopurines were distinct in clinic‐based studies (OR = 0.59, 95% CI 0.42‐0.82) and case‐control studies (OR = 0.40, 95% CI 0.26‐0.62), but not in population‐based studies (OR = 0.95, 95% CI 0.55‐1.62) and cohort studies (OR = 0.98, 95% CI 0.81‐1.18). Interestingly, studies conducted in Europe (OR = 0.48, 95% CI 0.31‐0.77), rather than in North America (OR = 0.91, 95% CI 0.67‐1.24), showed the protective effect of thiopurines. Conclusions This meta‐analysis revealed an antineoplastic effect of thiopurines on colorectal neoplasia in patients with IBD, particularly amongst patients with UC. Linked ContentThis article is linked to Qiu et al and Laharie and Riviere papers. To view these articles visit https://doi.org/10.1111/apt.14498 and https://doi.org/10.1111/apt.14475.