Crohn's disease and cancer: a population-based cohort study.

Background/aims: To study the association between Crohn's disease and cancer, we performed a population-based study of 1251 subjects with Crohn's disease diagnosed in Stockholm from 1955 to 1984 and followed in both the National Cancer Register and the National Cause-of-Death Register until 1989.

Methods: For comparisons, regional cancer incidence rates in Stockholm County were used together with individually computed person-years at risk in the Crohn's disease cohort.

Results: Overall, 69 malignancies occurred among 67 individuals as compared with 59.80 expected malignancies (standardized morbidity ratio [SMR] = 1.15; 95% confidence interval, 0.90-1.46). An excess number of cancers of the upper gastrointestinal tract (SMR, 3.05; 95% confidence interval, 1.67-5.11) was observed, mainly because of an increased number of cancers of the small intestine (SMR, 15.64; 95% confidence interval, 4.26-40.06). An increased occurrence of urinary bladder cancer was also observed (SMR, 2.68; 95% confidence interval, 1.08-5.53).

Conclusions: The occurrence of colorectal cancer was not increased.