RESUMEN
Colorectal cancer is a common disease in the United States. In the past 30 years, only limited improvements in stage of disease at the time of diagnosis and survival rates have been made. Research into genetic, environmental, and diet-related risk factors is promising but insufficient to serve as a foundation for preventive advice. The slowly progressive adenoma-carcinoma sequence is now commonly accepted. The American Cancer Society, Atlanta, Ga, and the National Cancer Institute, Bethesda, Md, advocate screening with annual fecal occult blood testing plus sigmoidoscopy every 3 to 5 years in persons 50 years old and older. The development of more cost-effective screening strategies is under study, with emphasis on targeting high-risk populations, determining optimal screening intervals, identifying the length of colon to study and by what means, and determining the surveillance needed in individuals who have had polyps removed.