Malignancies in Patients with Inflammatory Bowel Disease: Results from 20 Years of Follow-up in the IBSEN Study

Background and Aims: Whether patients with inflammatory bowel diseases [IBDs] have increased risk of developing cancer has been debated. The aims of the study were to determine the prevalence of intestinal/extraintestinal cancers in an IBD cohort 20 years after diagnosis and to assess whether these patients had an increased cancer-specific risk compared with a matched control population. Methods: Patients with ulcerative colitis [UC] and Crohn's disease [CD] diagnosed 1990-1993 have been prospectively followed up for 20 years. Follow-up visits were carried out 1, 5, 10, and 20 years after inclusion. Data on all cancer cases, deaths, and causes of death were collected from the Cancer Registry of Norway and from the Norwegian Cause of Death Registry. Results: In all, 756 patients [519 UC and 237 CD] were diagnosed with IBD. Increased risk of cancer was seen in UC patients (hazard ratio [HR] = 1.40, 95% confidence interval [CI] 1.08-1.81, p < 0.01), but not in CD patients [HR = 1.23, 95% CI 0.80-2.03, p = 0.30]. Stratified by gender, our data revealed a statistically increased risk for all cancers only in male UC patients compared with the controls [HR = 1.51, 95% CI 1.08-2.11, p = 0.017]. In both groups breast cancer was seen more often than expected. Conclusions: Male UC patients display an increased risk of development of colorectal cancer and, also all cancers combined, compared with the controls. In both UC and CD, standardized incidence ratio for breast cancer was increased.