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Medline ® Abstract for Reference 12

of 'Epidemiology, risk factors and the clinical approach to ER/PR negative, HER2-negative (Triple-negative) breast cancer'

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Parity, lactation, and breast cancer subtypes in African American women: results from the AMBER Consortium.
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Palmer JR, Viscidi E, Troester MA, Hong CC, Schedin P, Bethea TN, Bandera EV, Borges V, McKinnon C, Haiman CA, Lunetta K, Kolonel LN, Rosenberg L, Olshan AF, Ambrosone CB
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J Natl Cancer Inst. 2014;106(10) Epub 2014 Sep 15.
 
BACKGROUND: African American (AA) women have a disproportionately high incidence of estrogen receptor-negative (ER-) breast cancer, a subtype with a largely unexplained etiology. Because childbearing patterns also differ by race/ethnicity, with higher parity and a lower prevalence of lactation in AA women, we investigated the relation of parity and lactation to risk of specific breast cancer subtypes.
METHODS: Questionnaire data from two cohort and two case-control studies of breast cancer in AA women were combined and harmonized. Casepatients were classified as ER+ (n = 2446), ER- (n = 1252), or triple negative (ER-, PR-, HER2-; n = 567) based on pathology data; there were 14180 control patients. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated in polytomous logistic regression analysis with adjustment for study, age, reproductive and other risk factors.
RESULTS: ORs for parity relative to nulliparity was 0.92 (95% CI = 0.81 to 1.03) for ER+, 1.33 (95% CI = 1.11 to 1.59) for ER-, and 1.37 (95% CI = 1.06 to 1.70) for triple-negative breast cancer. Lactation was associated with a reduced risk of ER- (OR = 0.81, 95% CI = 0.69 to 0.95) but not ER+ cancer. ER- cancer risk increased with each additional birth in women who had not breastfed, with an OR of 1.68 (95% CI = 1.15 to 2.44) for 4 or more births relative to one birth with lactation.
CONCLUSIONS: The findings suggest that parous women who have not breastfed are at increased risk of ER- and triple-negative breast cancer. Promotion of lactation may be an effective tool for reducing occurrence of the subtypes that contribute disproportionately to breast cancer mortality.
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Slone Epidemiology Center at Boston University, Boston, MA (JRP, EV, TNB, LR); University of North Carolina Lineberger Cancer Center, Chapel Hill, NC (MAT, AFO); Roswell Park Cancer Institute, Buffalo, NY (CCH, CBA); University of Colorado Denver School of Medicine, Denver, CO (PS, VB); Rutgers Cancer Institute of New Jersey, New Brunswick, NJ (EVB); Boston University School of Public Health, Boston, MA (CM, KL); Department of Preventive Medicine and Norris Comprehensive Cancer Cencer, University of Southern California Keck School of Medicine, Los Angeles, CA (CAH); Department of Public Health Sciences, University of Hawaii School of Medicine, Honolulu, HI (LNK). jpalmer@bu.edu.
PMID