Malignancies in Inflammatory Bowel Disease: Frequency, Incidence and Risk Factors-Results from the Swiss IBD Cohort Study.

Background: Malignancy may occur as long-term complication of inflammatory bowel disease (IBD) due to different risk factors. We assessed prevalence and incidence of malignancy, and predictive factors in the Swiss IBD Cohort Study (SIBDCS).

Methods: All IBD patients in the SIBDCS were analyzed from a cross-sectional and longitudinal perspective. Patients with malignancies were compared to controls. Standardized incidence ratios (SIR) were calculated based on age-specific and sex-specific background rates.

Results: Malignancies were identified in 122 of 3119 patients (3.9%). In a logistic regression model, age (OR 1.04 per year), intestinal surgery (OR 3.34), and treatment with steroids (OR 2.10) were the main predictors for the presence of malignancy, while treatment with 5-ASA (OR 0.57) and biologics (OR 0.38) were protective. From a longitudinal perspective, 67 out of 2580 patients (2.6%) were newly diagnosed with malignancy during a follow-up of 12,420.8 years (median 4.9 years). While there was no increased risk for malignancy overall (SIR 0.93, 95% CI 0.72-1.18) and colorectal cancer (SIR 1.55, 95% CI 0.71-2.95), IBD patients had an increased risk for lymphoma (SIR 2.98, 95% CI 1.36-5.66) and biliary cancer (SIR 6.3, 95% CI 1.27-18.41). In a Cox regression model, age and recent use of immunomodulators were the main predictors for development of malignancies, while 5-ASA, biologics were protective.

Conclusions: IBD patients showed increased risk for lymphoma and biliary cancer, but not colorectal cancer and cancer overall. Age and recent use of immunomodulators were the main risk factors for malignancy, while aminosalicylates and biologics appear to be protective.