title: A prospective study of physical activity and breast cancer incidence in African-American women.
abstract: 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.
  
  
  CONCLUSIONS
  High levels of vigorous exercise or brisk walking may be associated with a reduction in incidence of breast cancer in African-American women.
  
  
  CONCLUSIONS
  These results provide informative data on a potential modifiable risk factor, exercise, for breast cancer in African-American women.
authors.affiliation: Slone Epidemiology Center, Boston University, Boston, Massachusetts. lrosenbe@bu.edu.
authors.forename: Lynn
authors.initials: L
authors.lastname: Rosenberg
authors.affiliation: Slone Epidemiology Center, Boston University, Boston, Massachusetts.
authors.forename: Julie R
authors.initials: JR
authors.lastname: Palmer
authors.affiliation: Slone Epidemiology Center, Boston University, Boston, Massachusetts.
authors.forename: Traci N
authors.initials: TN
authors.lastname: Bethea
authors.affiliation: Slone Epidemiology Center, Boston University, Boston, Massachusetts.
authors.forename: Yulun
authors.initials: Y
authors.lastname: Ban
authors.affiliation: Slone Epidemiology Center, Boston University, Boston, Massachusetts.
authors.forename: Kristen
authors.initials: K
authors.lastname: Kipping-Ruane
authors.affiliation: Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, District of Columbia.
authors.forename: Lucile L
authors.initials: LL
authors.lastname: Adams-Campbell
mesh_terms: D000328:Adult; D001741:Black or African American; D001943:Breast Neoplasms / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D011446:Prospective Studies; D011795:Surveys and Questionnaires
references.citation: Cancer Epidemiol Biomarkers Prev. 2010 Aug;19(8):2073-9
references.pmid: 20647407
references.citation: Crit Rev Oncol Hematol. 2010 Oct;76(1):44-52
references.pmid: 19800812
references.citation: Cancer. 2007 May 1;109(9):1721-8
references.pmid: 17387718
references.citation: Cancer. 1996 Apr 15;77(8):1465-71
references.pmid: 8608530
references.citation: Br J Sports Med. 2008 Aug;42(8):636-47
references.pmid: 18487249
references.citation: Sports Med. 1998 Nov;26(5):293-315
references.pmid: 9858394
references.citation: Ethn Dis. 2011 Autumn;21(4):406-11
references.pmid: 22428342
references.citation: Cancer Prev Res (Phila). 2013 Jun;6(6):566-76
references.pmid: 23576427
references.citation: Cancer Epidemiol Biomarkers Prev. 2011 Mar;20(3):454-63
references.pmid: 21364029
references.citation: Arch Intern Med. 2006 Dec 11-25;166(22):2478-83
references.pmid: 17159013
references.citation: Eur J Appl Physiol Occup Physiol. 1979 Sep;42(1):15-23
references.pmid: 499193
references.citation: Ethn Dis. 2006 Autumn;16(4):943-7
references.pmid: 17061751
references.citation: Cancer Epidemiol Biomarkers Prev. 2000 Jul;9(7):681-7
references.pmid: 10919738
references.citation: Arch Intern Med. 2007 Feb 26;167(4):408-15
references.pmid: 17325304
references.citation: Breast Cancer Res Treat. 2013 Feb;137(3):869-82
references.pmid: 23274845
references.citation: Am J Epidemiol. 2010 Dec 1;172(11):1286-91
references.pmid: 20937635
references.citation: Cancer Epidemiol Biomarkers Prev. 2005 Jan;14(1):227-36
references.pmid: 15668499
references.citation: Int J Obes Relat Metab Disord. 2000 Jun;24 Suppl 2:S71-3
references.pmid: 10997613
references.citation: Med Sci Sports Exerc. 1993 Jan;25(1):71-80
references.pmid: 8292105
references.citation: Acta Physiol Scand. 2002 Jun;175(2):147-56
references.pmid: 12028135
references.citation: Epidemiology. 2007 Jan;18(1):137-57
references.pmid: 17130685
references.citation: Am J Epidemiol. 2000 Apr 1;151(7):703-14
references.pmid: 10752798
references.citation: Am J Public Health. 2010 Nov;100(11):2288-95
references.pmid: 20864719
references.citation: Cancer Epidemiol Biomarkers Prev. 2005 Jan;14(1):2-19
references.pmid: 15668470
references.citation: Epidemiology. 1990 Jan;1(1):58-64
references.pmid: 2081241
references.citation: Breast Cancer Res. 2008;10(5):R92
references.pmid: 18976449
references.citation: Cancer Epidemiol Biomarkers Prev. 2013 Oct;22(10):1906-12
references.pmid: 24097200
references.citation: Cancer Epidemiol Biomarkers Prev. 2009 Jan;18(1):11-27
references.pmid: 19124476
references.citation: Nutr Cancer. 2010;62(4):425-35
references.pmid: 20432163
references.citation: Am J Clin Nutr. 2011 Jul;94(1):86-94
references.pmid: 21593501
references.citation: J Appl Physiol Respir Environ Exerc Physiol. 1978 Jan;44(1):109-14
references.pmid: 627490
references.citation: J Natl Cancer Inst. 1998 Jan 21;90(2):100-17
references.pmid: 9450570
references.citation: Cancer Epidemiol Biomarkers Prev. 2011 Sep;20(9):1883-91
references.pmid: 21846820
references.citation: Cancer Epidemiol Biomarkers Prev. 2009 Jan;18(1):289-96
references.pmid: 19124511
references.citation: J Natl Cancer Inst. 2005 Nov 16;97(22):1671-9
references.pmid: 16288120
references.citation: Cancer Epidemiol Biomarkers Prev. 2003 Nov;12(11 Pt 1):1143-52
references.pmid: 14652273
references.citation: Am J Epidemiol. 2009 Feb 15;169(4):428-34
references.pmid: 19056835
references.citation: Nutr Cancer. 2000;38(2):158-62
references.pmid: 11525592
references.citation: Ann Epidemiol. 1999 Jul;9(5):314-24
references.pmid: 10976858
references.citation: J Natl Med Assoc. 2001 Jul-Aug;93(7-8):267-75
references.pmid: 11491277
references.citation: J Natl Cancer Inst. 2005 Mar 16;97(6):439-48
references.pmid: 15770008
references.citation: JAMA. 2006 Jun 7;295(21):2492-502
references.pmid: 16757721
references.citation: Recent Results Cancer Res. 2011;188:125-39
references.pmid: 21253795
references.citation: Am J Prev Med. 2013 Sep;45(3):262-8
references.pmid: 23953351
references.citation: Cancer Epidemiol Biomarkers Prev. 2006 Jun;15(6):1170-8
references.pmid: 16775177
references.citation: Breast Cancer Res Treat. 2001 Jul;68(1):33-43
references.pmid: 11678307