Malignancies in patients with inflammatory bowel disease: a nationwide register study in Finland

OBJECTIVE. Patients with inflammatory bowel disease (IBD) are at increased risk of certain cancers. We assessed the long-term risks of malignancies among patients with IBD in Finland. METHODS. A total of 21,964 patients with IBD (16,649 with UC and 5315 with CD) from the database of the Social Insurance Institution were diagnosed in the periods 1987-1993 and 2000-2007 and followed up to the end of 2010 in a linkage with the nationwide Finnish Cancer Registry. The numbers of cancers observed were compared to those expected in general population and expressed as a standardized incidence ratio (SIR). RESULTS. Overall, male patients with CD and UC had a slightly increased risk of malignancies. Patients with UC were found to have an increased risk of colon (SIR 1.81, 95% confidence interval 1.46-2.21), rectal (1.76, 1.35-2.25), biliary tract (7.26, 4.37-11.1), and thyroid cancers (1.93, 1.28-2.79). The risk of colorectal cancer (CRC) was highest among the youngest UC patients. Patients with CD had a significantly increased SIR for cancers of the small intestine (9.97, 4.30-19.6), anus (9.51, 1.96-27.8), and biliary tract (4.93, 1.02-14.4), and also for myeloma (2.84, 1.14-5.85). In addition, the risk of basal cell skin cancer was increased in IBD (1.29, 1.16-1.43). Males with UC had a slightly decreased risk of lung and prostate cancers. CONCLUSIONS. The incidence of cancer among male patients with CD and CU was higher than that in general population. Patients with UC are at increased risk for CRC and biliary tract cancers. CRC risk was highest in the youngest patients.