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Background: Physical activity has been associated with reduced risk of breast cancer. Evidence on the association in African Americans is limited. Methods: With prospective data from the Black Women's Health Study, we assessed vigorous exercise and walking in relation to incidence of invasive breast cancer overall (n = 1,364), estrogen receptor–positive (ER+, n = 688) cancer, and estrogen receptor–negative (ER−, n = 405) cancer, based on 307,672 person-years of follow-up of 44,708 African-American women ages 30 years or older at enrollment. Cox proportional hazards models estimated incidence rate ratios (IRR) and 95% confidence intervals (CI). Results: Vigorous exercise at baseline was inversely associated with overall breast cancer incidence (Ptrend = 0.05): the IRR for ≥7 h/wk relative to Conclusion: High levels of vigorous exercise or brisk walking may be associated with a reduction in incidence of breast cancer in African-American women. Impact: These results provide informative data on a potential modifiable risk factor, exercise, for breast cancer in African-American women. Cancer Epidemiol Biomarkers Prev; 23(11); 2522–31. ©2014 AACR.

Diet quality has been inversely associated with overall mortality in white populations, but the evidence in African-American populations is limited.The goal of the present study was to assess diet quality in relation to all-cause mortality in the Black Women's Health Study, a follow-up study of African-American women begun in 1995.Data used in this study were obtained via biennial questionnaires from 1995 to 2011. Based on food-frequency questionnaire data collected in 1995 and 2001, we calculated an index-based diet quality score [Dietary Approaches to Stop Hypertension (DASH)] and derived dietary patterns (prudent and Western) with the use of factor analysis. We followed 37,001 women who were aged 30-69 y and free of cancer, cardiovascular disease, and diabetes at baseline for mortality through 2011. Multivariable Cox regression was used to estimate HRs and 95% CIs. Analyses were conducted in 2014.Based on a total of 1678 deaths during 16 y of follow-up, higher DASH scores were associated with reduced all-cause mortality (HR: 0.75; 95% CI: 0.63, 0.89 for highest vs. lowest quintiles). The DASH components most strongly associated with lower mortality were high intake of whole grains and low intake of red and processed meat. A Western dietary pattern, characterized by high intake of red and processed meat, was associated with increased all-cause mortality rates (HR: 1.37; 95% CI: 1.17, 1.60 for highest vs. lowest quintiles of score); a prudent dietary pattern was not associated with risk.A DASH-style diet high in intake of whole grains and low in consumption of red meat is associated with reduced mortality rates in healthy African-American women.