Background: Despite that an estimated 39-71% of colon cancer cases could be avoided through lifestyle modifications, colorectal cancer remains the third most commonly diagnosed cancer and the third leading cause of cancer death. Targeting the most prevalent lifestyle risk factors is a complementary strategy to screening in men and women 50+ years old, and should be the primary prevention strategy in younger people to reduce the incidence of and mortality from colorectal cancer. To prioritize targets for prevention, we, thus, evaluated the prevalence of modifiable risk factors for colorectal cancer in the U.S.

Methods: We used nationally representative data for non-Hispanic white (NHW), non-Hispanic black (NHB), and Mexican-American (MA) men and women (non-pregnant) 20-69 years old from the National Health and Nutrition Examination Survey (NHANES) conducted in 1999-2000, 2001-2002, 2003-2004, 2005-2006, and 2007-2008. We included lifestyle risk factors for which the evidence is convincing (WCRF/AICR, Surgeon General's Report): physical inactivity (<30 minutes of moderate or 20 minutes of vigorous activity on most days of the week), cigarette smoking (current), obesity (30+ kg/m2), and intake of red meat (1+ serving/day), processed meat (1+ serving/day), and alcohol (2+ servings/day). The prevalence of each risk factor was estimated applying weights to account for over-sampling, non-response, and post-stratification. We also calculated a score for the number of risk factors and evaluated differences in the score by sex, race/ethnicity and age using the chi-square test.

Results: At each time point, the most prevalent risk factor was physical inactivity (∼60%), followed by obesity (∼30%), red meat intake (∼30%) and smoking (∼25%). The prevalence of the risk factors did not decline over the 10 years and the ordering of their prevalences was stable. Overall, only 13% of adults had none of the risk factors, whereas 17% had 3 and 5% had 4-6 risk factors. Men (3: 20%, 4-6: 6%), who have higher colorectal cancer incidence and mortality rates, had more risk factors than women (3: 15%, 4-6: 4%; p=0.004). NHB adults (3: 20%, 4-6: 7%), who have the highest rates, had the most risk factors followed by NHW (3: 17%, 4-6: 5%), and MA (3: 14%, 4-6: 3%; p=0.06), who have the lowest rates of the three racial/ethnic groups. The number of risk factors did not differ among people aged 20-34 years (3: 16%, 4-6: 5%); 35-49 years (3: 18%, 4-6: 5%) or 50-69 years (3: 17%, 4-6: 4%; p=0.67), although which of the risk factors were the most prevalent differed slightly among the three age groups.

Conclusions: Eighty-seven percent of American adults have at least one colorectal cancer risk factor. The most prevalent risk factors are also risk factors for other common chronic diseases. Over the past 10 years, the prevalence of these risk factors has not declined. This constellation of risk factors should be targeted for intervention to reduce the burden of colorectal cancer and all other major chronic diseases.

Funding: Dr. Joshu was supported by NCI T32 CA009314.

Citation Information: Cancer Prev Res 2010;3(12 Suppl):B83.

Copyright © 2010, American Association for Cancer Research
2010