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Key words: cohort studies, Crohn's disease, inflammatory bowel diseases, intestinal neoplasms, risk.
Abstract
Objectives: The large number of studies of intestinal cancer among patients with Crohn's disease have provided inconsistent risk estimates in regard to risk of both colorectal and small intestinal cancer. We investigated incidence of cancer among Crohn's disease patients in comparison with the incidence in the general population of Denmark.
Methods: From the Danish National Registry of Patients we identi(R)ed 2645 patients who had been hospitalized with Crohn's disease during 1977+ or -1989. Cancer incidence for up to 17 years was determined in the cohort and compared to an expected number derived from national cancer incidence rates.
Results: The 15 observed cases of colorectal cancer were close to the expected number of 13.1 (SIR = 1.1; 95% CI 0.6+ or -1.9), whereas the (R)ve cases of small intestinal cancer (three adenocarcinomas and two carcinoids) observed corresponded to an 18-fold increased risk (SIR = 17.9; 95% CI 5.8+ or -42).
Conclusions: A potential excess of colorectal cancer among subgroups of patients with Crohn's disease was not detectable in the overall risk estimate for colorectal cancer. Only for small intestinal cancer was a signi(R)cantly elevated risk found among these patients hospitalized with Crohn's disease.
Introduction
Through the years the risk of cancers of the intestinal tract has been studied intensively in patients with Crohn's disease. Nevertheless, the relationship remains unclear. Several studies show an excess of cancer of the small intestine on the basis of only few cases of cancer [1+ or -4], while others are inconclusive [5+ or -9] (Table 1). Some studies report a clear 2 to 20-fold risk increase in the risk of colorectal cancer among patients with Crohn's disease [2, 3, 6, 8, 10], whereas other studies report no association between Crohn's disease and colorectal cancer [1, 4, 7, 9]. It has been suggested that an increased risk of colorectal cancer may be con(R)ned to the subset of Crohn's disease patients who have extensive, longstanding colitis [11, 12]. Several extraintestinal cancer types such as squamous cell skin cancer [5], nonHodgkin's lymphoma [13], vulvar cancer [13] and bladder cancer [1] have been found to occur more frequently among patients with Crohn's disease compared to the general population. However, none of...