Is adherence to diet, physical activity, and body weight cancer prevention recommendations associated with colorectal cancer incidence in African American women?

Purpose The purpose of this study was to evaluate whether adherence to the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) cancer prevention recommendations was associated with colorectal cancer incidence in the Black Women's Health Study (BWHS). Methods In this ongoing prospective cohort of African American women (analytic cohort n = 49,103), 354 incident colorectal cancers were diagnosed between baseline (1995) and 2011. Adherence scores for seven WCRF/AICR recommendations (adherent = 1 point, non-adherent level 1 = 0.5 points, non-adherent level 2 = 0 points) were created using questionnaire data and summed to an overall adherence score (maximum = 7). Recommendation adherence and colorectal cancer incidence were evaluated using baseline and time-varying data in Cox regression models. Results At baseline, 8.5 % of women adhered >4 recommendations. In time-varying analyses, the HR was 0.98 (95 % CI 0.84-1.15) per 0.5 point higher score and 0.51 (95 % CI 0.23-1.10) for adherence to >4 compared to <3 recommendations. Adherence to individual recommendations was not associated with colorectal cancer risk. Results were similar in models that considered baseline exposures only. Conclusions Adherence to cancer prevention recommendations was low and not associated with colorectal cancer risk among women in the BWHS. Research in diverse populations is essential to evaluate the validity of existing recommendations, and assess whether there are alternative recommendations that are more beneficial for cancer prevention in specific populations.