Age-specific Incidence of Breast Cancer Subtypes: Understanding the Black-White Crossover

J Natl Cancer Inst. 2012 Jul 18;104(14):1094-101. doi: 10.1093/jnci/djs264. Epub 2012 Jul 5.

Abstract

Background: Breast cancer incidence is higher among black women than white women before age 40 years, but higher among white women than black women after age 40 years (black-white crossover). We used newly available population-based data to examine whether the age-specific incidences of breast cancer subtypes vary by race and ethnicity.

Methods: We classified 91908 invasive breast cancers diagnosed in California between January 1, 2006, and December 31, 2009, by subtype based on tumor expression of estrogen receptor (ER) and progesterone receptor (PR)-together referred to as hormone receptor (HR)-and human epidermal growth factor receptor 2 (HER2). Breast cancer subtypes were classified as ER or PR positive and HER2 negative (HR(+)/HER2(-)), ER or PR positive and HER2 positive (HR(+)/HER2(+)), ER and PR negative and HER2 positive (HR(-)/HER2(+)), and ER, PR, and HER2 negative (triple-negative). We calculated and compared age-specific incidence rates, incidence rate ratios, and 95% confidence intervals by subtype and race (black, white, Hispanic, and Asian). All P values are two-sided.

Results: We did not observe an age-related black-white crossover in incidence for any molecular subtype of breast cancer. Compared with white women, black women had statistically significantly higher rates of triple-negative breast cancer at all ages but statistically significantly lower rates of HR(+)/HER2(-) breast cancers after age 35 years (all P < .05). The age-specific incidence of HR(+)/HER2(+) and HR(-)/HER2(+) subtypes did not vary markedly between white and black women.

Conclusions: The black-white crossover in breast cancer incidence occurs only when all breast cancer subtypes are combined and relates largely to higher rates of triple-negative breast cancers and lower rates of HR(+)/HER2(-) breast cancers in black vs white women.

Publication types

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

MeSH terms

  • Adult
  • African Americans / statistics & numerical data*
  • Age Factors
  • Aged
  • Asian Americans / statistics & numerical data
  • Biomarkers, Tumor / analysis*
  • Breast Neoplasms / chemistry
  • Breast Neoplasms / epidemiology*
  • Breast Neoplasms / pathology*
  • California / epidemiology
  • European Continental Ancestry Group / statistics & numerical data*
  • Female
  • Hispanic Americans / statistics & numerical data
  • Humans
  • Incidence
  • Middle Aged
  • Receptor, ErbB-2 / analysis
  • Receptors, Estrogen / analysis
  • Receptors, Progesterone / analysis
  • SEER Program
  • United States / epidemiology

Substances

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