Prevention of Colorectal Cancer by Endoscopic Polypectomy

Colon cancer, the second leading cause of death from cancer in the United States, will be diagnosed in 150 000 Americans this year and will claim approximately 56 000 lives [1]. Progress in treating this disease has been limited, and major advances in surgical and medical treatment are not anticipated in the immediate future. Thus, screening for the “early” curable stages of the disease in asymptomatic persons has become an important and relevant endeavor. As with all screening programs, most individuals who are screened will never get the disease. However, several case–control studies have suggested that screening with sigmoidoscopy, colonoscopy, and resultant polypectomy can substantially reduce the incidence of and mortality from colorectal cancer [2-4].

Adenomatous polyps are precursors of most colorectal cancers, and their prevalence increases with age. The chance of detecting adenomatous polyps at colonoscopy is generally independent of the indication for the procedure [5]. The practice of removing polyps at colonoscopy is based on the assumption that their removal prevents progression to cancer. This concept, often called the adenoma-carcinoma sequence, has never been directly proved [6]. The most compelling evidence substantiating the theory has come from the National Polyp Study, a cohort study in which the incidence of colorectal cancer in more than 1418 patients who had a complete colonoscopy and from whom one or more adenomatous polyps was removed was compared with the incidence in three reference groups [7]. Colonoscopic polypectomy resulted in an incidence of colorectal cancer that was 76% to 90% lower than expected. The results …