Abstract
A systematic search of the PubMed, Cochrane, Embase, and Web of Science databases was conducted to investigate the risk of urinary bladder cancer (BC) in patients with inflammatory bowel disease (IBD). We identified 168 articles, of which 11 met the inclusion and exclusion criteria. Our analysis included 165,176 patients with IBD, 491 of whom had BC. Overall, the pooled standardized incidence ratio (SIR) was 0.99 (95% CI: 0.87–1.12; I2 = 0%). Further subgroup analysis showed that BC risk was neither statistically higher for Crohn's disease (CD) (SIR: 1.19; 95% CI: 0.94–1.44; I2 = 0%) nor for patients with ulcerative colitis (UC) (SIR: 0.92; 95% CI: 0.77–1.06; I2 = 0%). In the analysis of two case-control studies providing data on BC in UC and CD combined, IBD patients seemed to have a higher risk of BC than non-IBD patients (relative risk: 1.25; 95% CI: 0.77–2.03; I2 = 37.5%). Although the overall risk of BC was not significantly increased among patients with IBD, there was a weak trend for the risk to be elevated in CD patients, indicating marginal significance. These findings may primarily be explained by the opposite effects of smoking on CD and UC as well as the immunosuppressive drugs these patients often take.
Highlights
Inflammatory bowel diseases (IBDs), including Crohn’s disease (CD) and ulcerative colitis (UC), are chronic idiopathic disorders causing inflammation of the gastrointestinal tract [1]
There were two case-control studies that provided data on bladder cancer (BC) in UC and CD combined, revealing that IBD patients seemed to have a higher risk of BC than non-IBD patients (RR: 1.25; 95% confidence intervals (CIs): 0.77–2.03; I2 = 37.5%; Figure 3)
Malignancies, both gastrointestinal and extraintestinal, are long-term complications in patients with IBD; they have a 30 and 10% higher long-term risk of invasive cancer than the general population, respectively, which might be a result of chronic inflammation and their use of immunosuppressive medications aimed at controlling inflammation [7, 8]
Summary
Inflammatory bowel diseases (IBDs), including Crohn’s disease (CD) and ulcerative colitis (UC), are chronic idiopathic disorders causing inflammation of the gastrointestinal tract [1]. The number of individuals affected by IBD remains unclear. Estimates suggest that more than 1.5 million and 2 million people are suffering from the disease in North America and Europe, respectively, with a rapidly growing number in Asia and other newly industrialized areas, placing heavy burdens on the health systems of countries in these areas [2, 3]. IBD is characterized by recurrent mucosal inflammation, bowel obstruction resulting from intestinal strictures, and internal or external fistulas or intestinal perforation [1]. IBD could involve extraintestinal organs and lead to corresponding manifestations. The most common extraintestinal manifestations include rheumatologic disorders, dermatologic disorders, ophthalmologic disorders, primary sclerosing cholangitis, nephrolithiasis, and thromboembolic events [4]
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