PT  - JOURNAL ARTICLE
AU  - Rosenberg, Lynn
AU  - Palmer, Julie R.
AU  - Bethea, Traci N.
AU  - Ban, Yulun
AU  - Kipping-Ruane, Kristen
AU  - Adams-Campbell, Lucile L.
TI  - A Prospective Study of Physical Activity and Breast Cancer Incidence in African-American Women
AID  - 10.1158/1055-9965.EPI-14-0448
DP  - 2014 Nov 01
TA  - Cancer Epidemiology Biomarkers & Prevention
PG  - 2522--2531
VI  - 23
IP  - 11
4099  - http://cebp.aacrjournals.org/content/23/11/2522.short
4100  - http://cebp.aacrjournals.org/content/23/11/2522.full
SO  - Cancer Epidemiol Biomarkers Prev2014 Nov 01; 23
AB  - 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 <1 h/wk was 0.74 (95% CI, 0.57–0.96). The association did not differ by ER status. Brisk walking for ≥7 h/wk was associated with a reduction similar to that for vigorous exercise. Vigorous exercise at the age of 30 years, 21 years, or in high school was not associated with breast cancer incidence. Sitting for long periods at work or watching TV was not significantly associated with breast cancer incidence. 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.