Increased risk of cancer in ulcerative colitis: A population-based cohort study

OBJECTIVE: There is an increased risk of colorectal cancer among patients w ith ulcerative colitis (UC). However, the overall and site specific cancer risks in these patients have been investigated to a limited extent. To stud y the association between UC and cancer, a population-based study of 1547 p atients with UC in Stockholm diagnosed between 1955 and 1984 was carried ou t. METHODS: The patients were followed in both the National Cancer Register an d the National Cause of Death Register until 1989. For comparisons, regiona l cancer incidence rates in Stockholm County were used together with indivi dually computed person-years at risk in the UC disease cohort. RESULTS: A total of 121 malignancies occurred among 97 individuals as compa red with 89.8 expected (standardized morbidity ratio [SMR] = 1.4; 95% confi dence interval (CI), 1.1-1.6). Overall, an excess number of colorectal canc ers (SMR, 4.1; 95% CI, 2.7-5.8), and hepatobiliary cancers in men (SMR = 6. 0; 95% CI, 2.8-11.1) associated with primary sclerosing cholangitis, was ob served. The risk of pulmonary cancer was decreased (SMR = 0.3; 95% CI, 0.1- 0.9). In all, 91 extracolonic malignancies were observed, compared with the 82.3 expected (SMR = 1.11; 95% CI, 0.9-1.3). CONCLUSIONS: In UC patients, the overall cancer incidence is increased main ly because of an increased incidence of colorectal and hepatobiliary cancer . This increase is partly counterbalanced by a decreased risk of pulmonary cancer compared with that in the general population. (C) 1999 by Am. Cell. of Gastroenterology.