Inflammatory bowel disease, cancer and medication: Cancer risk in the Dutch population-based IBDSL cohort

The management of inflammatory bowel disease (IBD) has changed since the mid-1990s (e.g., use of thiopurines/anti-TNF alpha agents, improved surveillance programs), possibly affecting cancer risk. To establish current cancer risk in IBD, updates are warranted from cohorts covering this time span, and detailed enough to study associations with phenotype and medication. We studied intestinal-, extra-intestinal-and overall cancer risk in the Dutch population-based IBDSL cohort. In total, 1,157 Crohn's disease (CD) and 1,644 ulcerative colitis (UC) patients were diagnosed between 1991 and 2011, and followed until 2013. Standardized incidence ratios (SIRs) were calculated for CD and UC separately, as well as for gender- ,phenotype-, disease duration-, diagnosis era-and medication groups. We found an increased risk for colorectal cancer in CD patients with colon involvement (SIR 2.97; 95% CI 1.08-6.46), but not in the total CD or UC population. In addition, CD patients were at increased risk for hematologic-(2.41; 1.04-4.76), overall skin-(1.55; 1.06-2.19), skin squamous cell-(SCC; 3.83; 1.83-7.04) and overall cancer (1.28; 1.01-1.60), whereas UC patients had no increased risk for extra-intestinal-and overall cancer. Finally, in a medication analysis on CD and UC together, long-term immunosuppression exposure (> 12 months) was associated with an increased risk for hematologic cancer, non-Hodgkin lymphoma, SCC and overall cancer, and this increase was mainly attributed to thiopurines. IBD patients with long-term immunosuppression exposure can be considered as having a higher cancer risk, and our data support the advice in recent IBD guidelines to consider skin cancer screening in these patients.