We found that there are many opportunities for the primary prevention of colorectal cancer in the United States. In 2007–2008, 81% percent of US adults, aged 20–69, had at least one modifiable risk factor for colorectal cancer. In the Annual Report to the Nation, it was estimated that screening, in combination with a considerable reduction in the 2000 prevalence of lifestyle risk factors could have a significant impact on colorectal cancer mortality (3
). Yet, we observed no notable improvement in the prevalence of a subset of those risk factors in the decade between 1999 and 2008. The combination of sub-optimal screening rates and a steady prevalence of lifestyle risk factors suggests that colorectal cancer rates will not decrease to the extent possible in the near future. The most prevalent modifiable risk factors for colorectal cancer, like obesity, are not novel; these are the same risk factors as for other chronic diseases, like diabetes and cardiovascular disease. Our findings do not signify a need for specialized colorectal cancer lifestyle interventions, but they do provide additional evidence for the need for the early intervention and targeted prevention and wellness services to be developed as part of the Patient Protection and Affordable Care Act of 2010 (4
In the clinical setting, the guidelines for colorectal cancer prevention focus on screening the average risk adult at age 50 (16
). However, our data indicate that the conversation about colorectal cancer risk and prevention needs to start much earlier. We observed that more than 15% of those younger than 50, and thus, not recommended for screening, had 3 or more risk factors. In contrast to overall rates, colorectal cancer incidence has increased in those younger than 50 (7
). Alerting younger adults about their colorectal cancer risk based on lifestyle factors provides an opportunity for change. Awareness of personal risk due to lifestyle risk factors may also increase awareness of the importance of adherence to screening guidelines at the appropriate age. Indeed, a growing body of evidence supports the benefit of simultaneously addressing multiple health behaviors in healthcare settings (17
). Because colorectal cancer screening is a complex behavior (20
); more research is needed to determine whether increased awareness of lifestyle risk factors among young adults would influence future screening behavior.
Our findings also show that the population sub-groups with the highest burden of colorectal incidence and mortality also have the greatest opportunity for primary prevention through lifestyle modification. The total burden of colorectal cancer risk factors mirrored colorectal cancer incidence and mortality rates by sex and race/ethnicity. Men had a higher total number of risk factors than women; men also have higher colorectal cancer incidence and mortality rates than women (21
). Non-Hispanic blacks had the highest total number of risk factors among the race and ethnicity groups; and African Americans have the highest colorectal cancer incidence and mortality (21
). Providing access to resources that encourage appropriate lifestyle changes, as well as increasing access to screening, may improve colorectal cancer rates in those with the highest burden.
We used nationally representative data to estimate the separate and joint prevalences of risk factors, overall, and by sex, race/ethnicity, and age over a 10-year period. The data were cross-sectional; individuals were not followed over time or for colorectal cancer outcomes. The prevalence of current smoking that we estimated in NHANES 2007–2008 was higher than that reported in the 2007 National Health Interview Survey (22
); our estimate is for a narrower age range (20–69 years versus 18+). We were unable to fully evaluate physical inactivity time trends because its assessment was changed in the 2007–2008 NHANES survey relative to the 1999–2006 surveys. In addition, the 1999–2006 surveys incompletely assessed occupational activity, an activity type that may differ across sex, race/ethnicity, age and time. Red meat and processed meat intakes were evaluated using the current state-of-art, one-day, 24-hour diet recall, the United States Department of Agriculture’s Automated Multiple Pass Method (23
). We used a single 24-hour diet recall because multiple days were not available for two of the five NHANES cycles evaluated. While multiple days of 24-hour diet recall are needed to assess individuals’ usual intake, this single 24-hour recall is a robust method to describe the average dietary intake of a group (23
Improved clinical and community preventive services are a major aspect of the National Prevention Strategy. Colorectal cancer is a disease with many opportunities for prevention. Increasing national screening rates is an important strategy for reducing the burden of colorectal cancer, but it should not be the only strategy. We found that the vast majority American adults have at least one modifiable colorectal cancer risk factor. Further, a sizable proportion of those younger than 50 years have several colorectal cancer risk factors. When advising the public about risks associated with factors like obesity and cigarette smoking, colorectal cancer should be included in the discussion. Increasing the public’s awareness that these factors also impact colorectal cancer risk may enhance efforts to modify lifestyle, and may further encourage adherence to screening guidelines. The most successful national strategy for colorectal cancer prevention will likely include complementary approaches of both screening and lifestyle modification.