TY - JOUR
T1 - Parity, lactation, and breast cancer subtypes in African American Women
T2 - Results from the AMBER Consortium
AU - Palmer, Julie R.
AU - Viscidi, Emma
AU - Troester, Melissa A.
AU - Hong, Chi Chen
AU - Schedin, Pepper
AU - Bethea, Traci N.
AU - Bandera, Elisa V.
AU - Borges, Virginia
AU - McKinnon, Craig
AU - Haiman, Christopher A.
AU - Lunetta, Kathryn
AU - Kolonel, Laurence N.
AU - Rosenberg, Lynn
AU - Olshan, Andrew F.
AU - Ambrosone, Christine B.
N1 - Funding Information:
This work was supported by the National Institutes of Health (NIH) (grants P01 CA151135 to CBA, AFO, JRP; R01 CA058420 to LR; UM1 CA164974 to LR; R01 CA100598 to CBA, EVB; UM1 CA164973 to LNK; RO1 CA54281 to LNK; P50 CA58223 to Charles Perou at UNC) and the University Cancer Research Fund of North Carolina.
Publisher Copyright:
© The Author 2014.
PY - 2014/10/1
Y1 - 2014/10/1
N2 - 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. Case patients were classified as ER+ (n = 2446), ER- (n = 1252), or triple negative (ER-, PR-, HER2-; n = 567) based on pathology data; there were 14 180 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.
AB - 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. Case patients were classified as ER+ (n = 2446), ER- (n = 1252), or triple negative (ER-, PR-, HER2-; n = 567) based on pathology data; there were 14 180 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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U2 - 10.1093/jnci/dju237
DO - 10.1093/jnci/dju237
M3 - Article
C2 - 25224496
AN - SCOPUS:84985006685
SN - 0027-8874
VL - 106
JO - Journal of the National Cancer Institute
JF - Journal of the National Cancer Institute
IS - 10
M1 - dju237
ER -