Opportunities for the primary prevention of colorectal cancer in the United States.

Several studies indicate that screening in combination with lifestyle modification may produce a greater reduction in colorectal cancer rates than screening alone. To identify national opportunities for the primary prevention of colorectal cancer, we assessed the prevalence of modifiable lifestyle risk factors in the United States. We used nationally representative, cross-sectional data from 5 NHANES cycles (1999-2000, n = 2,753; 2001-2002, n = 3,169; 2003-2004, n = 2,872; 2005-2006, n = 2,993; 2007-2008, n = 3,438). We evaluated the 5 colorectal cancer risk factors deemed "convincing" by the World Cancer Research Fund (obesity, physical inactivity, intake of red meat, processed meat, alcohol), and cigarette smoking, a "suggestive" risk factor in the Surgeon General's report. We estimated the prevalence of each risk factor separately and jointly, and report it overall, and by sex, race/ethnicity, age, and year. In 2007 to 2008, 81% percent of U.S. adults, aged 20 to 69 years, had at least one modifiable risk factor for colorectal cancer. More than 15% of those younger than 50 years had 3 or more risk factors. There was no change in the prevalence of risk factors between 1999 and 2008. The most common risk factors were risk factors for other chronic diseases. Our findings provide additional support for the prioritization of preventive services in health care reform. Increasing awareness, especially among young adults, that lifestyle factors influence colorectal cancer risk, and other chronic diseases, may encourage lifestyle changes and adherence to screening guidelines. Complementary approaches of screening and lifestyle modification will likely provide the greatest reduction of colorectal cancer.