Background and aims: Cancer risk in inflammatory bowel disease [IBD] is still debated. In a prospective, multicentre, nested case-control study, we aimed to characterise incident cases of cancer in IBD. The role of immunomodulators vs clinical characteristics of IBD as risk factors for cancer was also investigated.
Materials and methods: From January 2012 to December 2014, each IBD patient with incident cancer was matched with two IBD patients without cancer for: IBD type, gender, and age. Risk factors were assessed by multivariate regression analysis.
Results: IBD patients considered numbered 44619: 21953 Crohn's disease [CD], 22666 ulcerative colitis [UC]. Cancer occurred in 174 patients: 99 CD [CD-K], 75 UC [UC-K]. Controls included 198 CD [CD-C], 150 UC [UC-C]. Cancer incidence in IBD was 3.9/1000, higher in CD (4.5/1000 [99/21,953]) than in UC (3.3/1000 [75/22,666]; p = 0.042). Cancers involved: digestive system [36.8%], skin [13.2%], urinary tract [12.1%], lung [8.6%], breast [8%], genital tract [6.9%], thyroid [4.6%], lymphoma [3.5%], others [6.3%]. In CD, penetrating behaviour and combined thiopurines and tumour necrosis factor alpha [TNFα] antagonists were risk factors for cancer overall: odds ratio [OR] (95% confidence interval [CI] 2.33 [1.01-5.47]); 1.97 [1.1-3.5]; and for extracolonic cancers 3.9 [1.56-10.1]; 2.15 [1.17-4.1], respectively. In UC, risk factors were pancolitis and disease-related surgery for cancer overall (OR: 2.52 [1.26-5.1]; 5.09 [1.73-17.1]); disease-related surgery for colorectal cancer [CRC] (OR 3.6 [1.0-12]); and extensive and left-sided vs distal UC for extracolonic cancers (OR: 2.55 [1.15-5.9]; 2.6 [1.04-6.6]), respectively.
Conclusions: In a multicentre study, penetrating CD and extensive UC were risk factors for cancer overall. Cancer incidence was higher in CD than in UC.
Keywords: Inflammatory bowel disease; cancer risk; phenotype.
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