Objective: To assess the incidence of underlying malignancy in patients with a diagnosis of diverticular disease of the colon.
Design: Retrospective cohort study.
Setting: University hospital, Sweden.
Subjects: 7159 patients discharged from hospital with a first diagnosis of diverticulosis or diverticulitis in central Sweden 1965-1983.
Intervention: The cohort was followed up for two years for the occurrence of cancer.
Main outcome measure: Cancer incidence.
Results: A total of 372 cancer cases were identified standard incidence ratio = 2.4; 95% confidence interval 2.2 to 2.7). Sites at excess risk during the first year were: colon and rectum, pancreas, prostate, stomach, lymphatic and haemopoietic tissue, liver and bile ducts, ovary and lung, with the highest excess risk in the left colon (standard incidence ratio = 17.8; 95% CI 12.7 to 24.1).
Conclusion: Malignant diseases, especially colorectal cancer, are relatively common among patients with a clinical diagnosis of diverticulosis or diverticulitis of the colon. This may indicate a need for a change in current clinical practice.