A population-based study examining the risk of malignancy in patients diagnosed with inflammatory bowel disease
Recent studies suggest an increased risk of malignancy in patients with inflammatory bowel disease (IBD), although the findings were inconsistent. We used data from the clinical practice research datalink (CPRD) to further examine this association. Patients with a first-time diagnosis of IBD were randomly matched to an equally sized IBD-free comparison group. Multivariable adjusted hazard ratios (AHRs) for cancer risk were estimated using Cox’s proportional hazard regression. A nested case–control analysis comprising IBD patients only was then conducted using conditional logistic regression to estimate the risk of cancer development according to IBD severity, disease duration and IBD therapy. We identified 1077 cancers among 39,294 IBD or IBD-free patients followed between 1995 and 2012. There was no association between IBD and overall risk of cancer [AHR 1.11, 95 % confidence interval (CI) 0.98–1.25], but a borderline increase in the risk of lymphoproliferative malignancies was observed in patients with IBD (AHR 1.49, 95 % CI 1.00–2.23). Aminosalicylate use was significantly associated with reduced risk of all cancers [adjusted odds ratio (AOR), 0.72, 95 % CI 0.54–0.96], of intestinal cancer (AOR 0.33, 95 % 0.12–0.89) and of prostate cancer (AOR 0.32, 95 % 0.13–0.80). There was no increased risk of cancer overall in individuals with IBD compared to IBD-free individuals. Consistent with previous findings, a reduction in cancer risk was observed in IBD patients using aminosalicylates, with a substantial reduction in prostate cancer risk. Further large-scale studies examining the relationship between IBD therapy and cancer risk appear to be warranted.