A Pooled Case-only Analysis of Reproductive Risk Factors and Breast Cancer Subtype Among Black Women in the Southeastern United States

Cancer Epidemiol Biomarkers Prev. 2021 Jul;30(7):1416-1423. doi: 10.1158/1055-9965.EPI-20-1784. Epub 2021 May 4.

Abstract

Background: We investigated the association between reproductive risk factors and breast cancer subtype in Black women. On the basis of the previous literature, we hypothesized that the relative prevalence of specific breast cancer subtypes might differ according to reproductive factors.

Methods: We conducted a pooled analysis of 2,188 (591 premenopausal, 1,597 postmenopausal) Black women with a primary diagnosis of breast cancer from four studies in the southeastern United States. Breast cancers were classified by clinical subtype. Case-only polytomous logistic regression models were used to estimate ORs and 95% confidence intervals (CI) for HER2+ and triple-negative breast cancer (TNBC) status in relation to estrogen receptor-positive (ER+)/HER2- status (referent) for reproductive risk factors.

Results: Relative to women who had ER+/HER2- tumors, women who were age 19-24 years at first birth (OR, 1.78; 95% CI, 1.22-2.59) were more likely to have TNBC. Parous women were less likely to be diagnosed with HER2+ breast cancer and more likely to be diagnosed with TNBC relative to ER+/HER2- breast cancer. Postmenopausal parous women who breastfed were less likely to have TNBC [OR, 0.65 (95% CI, 0.43-0.99)].

Conclusions: This large pooled study of Black women with breast cancer revealed etiologic heterogeneity among breast cancer subtypes.

Impact: Black parous women who do not breastfeed are more likely to be diagnosed with TNBC, which has a worse prognosis, than with ER+/HER2- breast cancer.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • African Americans / statistics & numerical data*
  • Aged
  • Aged, 80 and over
  • Biomarkers, Tumor / analysis
  • Biomarkers, Tumor / metabolism
  • Breast / pathology*
  • Breast Neoplasms / diagnosis
  • Breast Neoplasms / epidemiology*
  • Breast Neoplasms / pathology
  • Female
  • Humans
  • Middle Aged
  • Prospective Studies
  • Receptor, ErbB-2 / analysis
  • Receptor, ErbB-2 / metabolism
  • Receptors, Estrogen / analysis
  • Receptors, Estrogen / metabolism
  • Receptors, Progesterone / analysis
  • Receptors, Progesterone / metabolism
  • Reproductive History*
  • Risk Factors
  • Southeastern United States / epidemiology
  • Young Adult

Substances

  • Biomarkers, Tumor
  • Receptors, Estrogen
  • Receptors, Progesterone
  • ERBB2 protein, human
  • Receptor, ErbB-2