Abstract PD4-03: Adherence to diet, physical activity and body composition guidelines and breast cancer in the black women's health study
Authors: Nomura SJO , Yu J , Dash C , Rosenberg L , Palmer J , Adams-Campbell L 
Published: May 2016

Background: While breast cancer incidence rates have declined in non-Hispanic Caucasian populations, rates have remained stable in African American women, who are often affected by more aggressive subtypes. Previous studies have found that adherence to the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) cancer prevention recommendations, and the similar American Cancer Society (ACS) guidelines, is associated with lower incidence of breast cancer. However, few African American women were included in these studies, and guidelines are based primarily on research among Caucasian women.

Objective: To evaluate the association between adherence to the WCRF/AICR cancer prevention recommendations and breast cancer incidence among African American women.

Design: The Black Women's Health Study is an ongoing prospective study of African American women from across the United States who were 21-69 years of age at baseline in 1995. They are followed biennially through health questionnaires. Among 49,103 women who were free of cancer at baseline and who provided relevant dietary and data on the baseline questionnaire, 1,827 incident cases of breast cancer were ascertained during follow-up through 2011. Questionnaire data on physical activity, body composition and diet were used to compute adherence scores for seven WCRF/AICR recommendations involving those factors. For each individual recommendation, participants were categorized as adherent (1 point), partially adherent (0.5 points) or non-adherent (0 points). Scores were summed to a total adherence score (maximum score: 7 points) and a diet only adherence score (maximum score: 5 points). Adherence scores (categorical and continuous) based on baseline data only and on time-varying data were assessed in relation to breast cancer incidence using Cox proportional hazards regression models, with control for potential confounding factors.

Results: In the analytic cohort, 8.5% of participants had an adherence score of 4.5-7.0, while 46% had a score less than 3.0. For individual recommendations, 15.2% were adherent to body weight recommendations, 24.7% were adherent to physical activity, and 5.4% were adherent to more than 4 diet recommendations. Participants were most likely to adhere to the alcohol recommendation (94.3%). In the time varying model, higher overall adherence (per 0.5 unit increase) was associated with lower breast cancer incidence (HR: 0.90, 95% CI: 0.84-0.96), with greater adherence to diet overall, physical activity, sugar beverage intake, and red and processed meat recommendations all significantly associated with reduced risk. The adherence score based on baseline variables was not associated with significantly reduced risk (HR: 0.96, 95% CI: 0.90-1.02), although meeting physical activity recommendations was associated.

Conclusions: Our findings suggest that adherence to the WCRF/AICR guidelines may lower risk of developing breast cancer in African American women. However, body weight and alcohol, factors that are widely considered important for breast cancer prevention appear to be less relevant in this population.

Citation Format: Nomura SJO, Yu J, Dash C, Rosenberg L, Palmer J, Adams-Campbell L. Adherence to diet, physical activity and body composition guidelines and breast cancer in the black women's health study. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr PD4-03.