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Epidemiology of Basal-Like and Luminal Breast Cancers among Black Women in the AMBER Consortium


Benefield, Halei C.; Zirpoli, Gary R.; Allott, Emma H.; Shan, Yue; Hurson, Amber N.; Omilian, Angela; Khoury, Thaer; Hong, Chi-Chen; Olshan, Andrew F.; & Bethea, Traci N., et al. (2021). Epidemiology of Basal-Like and Luminal Breast Cancers among Black Women in the AMBER Consortium. Cancer Epidemiology, Biomarkers & Prevention, 30(1), 71-79.


BACKGROUND: Evidence suggests etiologic heterogeneity among breast cancer subtypes. Previous studies with six-marker immunohistochemical classification of intrinsic subtypes included small numbers of black women.
METHODS: Using centralized laboratory results for estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 (HER2), proliferation marker Ki-67, epidermal growth factor receptor (EGFR), and cytokeratin (CK)5/6, we estimated case-only and case-control odds ratios (ORs) for established breast cancer risk factors among cases (n=2,354) and controls (n =2,932) in the African American Breast Cancer Epidemiology and Risk (AMBER) consortium. ORs were estimated by ER status and intrinsic subtype using adjusted logistic regression.
RESULTS: Case-only analyses by ER status showed etiologic heterogeneity by age at menarche, parity (versus nulliparity), and age at first birth. In case-control analyses for intrinsic subtype, increased body mass index (BMI) and waist-to-hip (WHR) ratio were associated with increased risk of luminal A subtype, while older age at menarche and parity, regardless of breastfeeding, were associated with reduced risk. For basal-like cancers, parity without breastfeeding and increasing WHR were associated with increased risk, whereas breastfeeding and age ≥ 25 years at first birth were associated with reduced risk among parous women. Basal-like and ER-/HER2+ subtypes had earlier age-at-incidence distribution relative to luminal subtypes.
CONCLUSIONS: Breast cancer subtypes show distinct etiologic profiles in the AMBER consortium, a study of over 5,000 black women with centrally assessed tumor biospecimens.
IMPACT: Among black women, high WHR and parity without breastfeeding are emerging as important intervention points to reduce the incidence of basal-like breast cancer.


Reference Type

Journal Article

Article Type


Year Published


Journal Title

Cancer Epidemiology, Biomarkers & Prevention


Benefield, Halei C.
Zirpoli, Gary R.
Allott, Emma H.
Shan, Yue
Hurson, Amber N.
Omilian, Angela
Khoury, Thaer
Hong, Chi-Chen
Olshan, Andrew F.
Bethea, Traci N.
Bandera, Elisa V.
Palmer, Julie R.
Ambrosone, Christine B.
Troester, Melissa A.

Data Set/Study

African American Breast Cancer Epidemiology and Risk (AMBER) consortium
Carolina Breast Cancer Study
Black Women’s Health Study
Women's Circle of Health Study
Multi-Ethnic Cohort


United States of America