INCIDENCE OF COLORECTAL-CANCER AND ALL-CAUSE MORTALITY IN NONSELECTEDPATIENTS WITH ULCERATIVE-COLITIS AND INDETERMINATE COLITIS IN MALMO, SWEDEN

Cancer morbidity and all cause mortality were studied prospectively in all patients with definite and probable ulcerative colitis and indete rminate colitis diagnosed from 1958 to 1982, in the city of Malmo, Swe den. The follow-up to Jan. 1, 1990 was complete for all but ten patien ts. Nine of the 471 patients with ulcerative colitis and three of the 100 patients with indeterminate colitis developed colo-rectal cancer. The incidence of colorectal cancer in ulcerative colitis was 1.4 per 1 000 person-years. The observed number of cases was 2.1 times higher th an expected; (95% C.I. 1.0-4.1), based on the age- and sex-specific ca ncer incidence in the city during the study period. Indeterminate coli tis was associated with a higher colo-rectal cancer risk than ulcerati ve colitis; 2.4 per 1000 person-years; (SMR 8.6, 95% C.I. 1.8-25.1). B oth conditions were associated with a slight increased mortality rate, for ulcerative colitis 12.6 per 1000 person-years: (SMR 1.3, 95% C.I. 1.0-1.5), and for indeterminate colitis 11.7 per 1000 person-years; ( SMR 2.7, 95% C.I. 1.6-4.4). Complications of colitis were the main cau se of death in both groups. The cancer risk was related to extent of d isease, duration of disease and female gender. Ten out of the 12 cases with cancer had or developed total colitis. However, only seven of th e 134 cases with total ulcerative colitis and two of 87 cases with tot al indeterminate colitis developed cancer. Considering these low frequ encies and the low cancer incidence per 1000 person years, it is sugge sted that proctocolectomy to prevent cancer is not to be recommended s imply at the basis of the extent of the disease.