Colorectal cancer is the second leading cause of cancer death in North America, according to background information in the article. Evidence exists that screening asymptomatic populations beginning at age 50 years can reduce death due to colorectal cancer and that removal of precursor tumors may reduce the incidence of colorectal cancer. Identification of important risk factors for advanced colonic tumors could inform both risk stratification and development of risk reduction strategies. Few studies have evaluated risk factors for advanced colorectal tumors in asymptomatic individuals, compared risk factors between persons with and without polyps, or included most purported risk factors in a multivariate analysis.
David A. Lieberman, M.D., of the Department of Veterans Affairs Medical Center, Portland, Ore., and colleagues conducted a study to determine the risk factors associated with advanced colorectal neoplasia (tumors) in a group of asymptomatic persons with complete colonoscopy. The study, conducted between February 1994 and January 1997, included 3,121 asymptomatic patients aged 50 to 75 years from 13 Veterans Affairs medical centers. All participants had complete colonoscopy to determine the prevalence of advanced neoplasia. Variables examined included history of first-degree relative with colorectal cancer, prior cholecystectomy (surgical removal of the gall bladder), serum cholesterol level, physical activity, smoking, alcohol use, and dietary factors.
A total of 329 participants had advanced neoplasia and 1,441 had no polyps. The researchers found positive associations for history of a first-degree relative with colorectal cancer (66 per
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JAMA and Archives Journals