Greater Observance of Cancer Prevention Recommendations Linked to Decreased CRC Risk

January 20, 2020

Similar health risks for colorectal cancer were observed in both African Americans and whites, though this study indicated that benefit from greater adherence may be higher at the population level for African Americans.

A study published in Cancer suggests that greater adherence to the World Cancer Research Fund (WCRF)/American Institute for Cancer Research (AICR) cancer prevention recommendations appears to be associated with decreased colorectal cancer (CRC) risk for both African Americans and whites. 

Though similar health risks for CRC were observed in both African Americans and whites, researchers found a higher prevalence of CRC risk factors among African Americans, indicating that the benefit of compliance at the population level may be higher in African Americans.

“Establishing the strength of associations between exposures and disease burden across subpopulations, including race, is important because it could help us to tailor public health policies and guidelines for certain groups,” the authors wrote. 

In 2018, WCRF and AICR published an updated list of 10 recommendations for cancer prevention based on a review of epidemiologic studies on body weight, physical activity, diet, and supplement use. However, these guidelines veered the emphasis of the recommendations toward considering these risk factors as an integrated pattern of behaviors, no longer including salt consumption as an individual recommendation. 

In this cohort of 368 incident CRC cases (268 among whites and 100 among African Americans) identified between 1987 and 2012, a baseline adherence score was created for 7 WCRF/AICR guidelines from the 2018 expert report (each contributing 0, 0.5, or 1 point to the score, with higher scores corresponding to greater adherence). After adjustments for age, sex, race, center, smoking, education, intake of aspirin, calcium, total calories, diabetes status, and, in women, hormone replacement therapy, greater abidance was correlated with a reduced risk of CRC (12% per unit of adherence score). 

The hazard ratios (HRs) per 1-unit increment in score were 0.88 (95% CI, 0.80-0.97) for the whole cohort, 0.89 (95% CI, 0.73-1.09) for African Americans, and 0.88 (95% CI, 0.77-0.99) for whites. Similar associations between higher adherence scores and decreased cancer risk were observed for men and women and for colon cancer (14% per unit of the adherence score), but not for rectal cancer. 

The results also indicated that the BMI score component was an important contributor to the association between the adherence score and risk of CRC. Additionally, the prevalence of several CRC risk factors, including BMI, physical activity, intake of sugary beverages, intake of dietary fiber, and fruit and vegetable intake, was higher in African Americans than white, resulting in lower adherence scores for the WCRF/AICR recommendations for cancer prevention.

Given these data, the authors suggested that, “effective public health initiatives to promote healthy lifestyle behaviors that might decrease CRC incidence should be beneficial for both whites and African Americans.”

According to the study, CRC is the third most commonly diagnosed cancer in men and women in the US. Moreover, African Americans are at increased risk of developing CRC, with incidence rates approximately 21.8% higher among African Americans than whites in 2015. Though precise reasons for this discrepancy are unknown, researchers suggested that it could be due to disparities in screening rates, socioeconomic status, and the prevalence of risk factors correlated with CRC (e.g. diet, obesity, and physical activity) or to a different strength of association between these risk factors and incidence of CRC among African Americans in comparison with whites.

Reference:

Onyeaghala G, Lintelmann AK, Joshu CE, et al. Adherence to the World Cancer Research Fund/American Institute for Cancer Research Cancer Prevention Guidelines and Colorectal Cancer Incidence Among African Americans and Whites: The Atherosclerosis Risk in Communities Study. Cancer. doi:10.1002/cncr.32616.