Racial Differences in PAM50 Subtypes in the Carolina Breast Cancer Study.

Journal Article (Journal Article)

BACKGROUND: African American breast cancer patients have lower frequency of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2 (HER2)-negative disease and higher subtype-specific mortality. Racial differences in molecular subtype within clinically defined subgroups are not well understood. METHODS: Using data and biospecimens from the population-based Carolina Breast Cancer Study (CBCS) Phase 3 (2008-2013), we classified 980 invasive breast cancers using RNA expression-based PAM50 subtype and recurrence (ROR) score that reflects proliferation and tumor size. Molecular subtypes (Luminal A, Luminal B, HER2-enriched, and Basal-like) and ROR scores (high vs low/medium) were compared by race (blacks vs whites) and age (≤50 years vs > 50 years) using chi-square tests and analysis of variance tests. RESULTS: Black women of all ages had a statistically significantly lower frequency of Luminal A breast cancer (25.4% and 33.6% in blacks vs 42.8% and 52.1% in whites; younger and older, respectively). All other subtype frequencies were higher in black women (case-only odds ratio [OR] = 3.11, 95% confidence interval [CI] = 2.22 to 4.37, for Basal-like; OR = 1.45, 95% CI = 1.02 to 2.06, for Luminal B; OR = 2.04, 95% CI = 1.33 to 3.13, for HER2-enriched). Among clinically HR+/HER2- cases, Luminal A subtype was less common and ROR scores were statistically significantly higher among black women. CONCLUSIONS: Multigene assays highlight racial disparities in tumor subtype distribution that persist even in clinically defined subgroups. Differences in tumor biology (eg, HER2-enriched status) may be targetable to reduce disparities among clinically ER+/HER2- cases.

Full Text

Duke Authors

Cited Authors

  • Troester, MA; Sun, X; Allott, EH; Geradts, J; Cohen, SM; Tse, C-K; Kirk, EL; Thorne, LB; Mathews, M; Li, Y; Hu, Z; Robinson, WR; Hoadley, KA; Olopade, OI; Reeder-Hayes, KE; Earp, HS; Olshan, AF; Carey, LA; Perou, CM

Published Date

  • February 1, 2018

Published In

Volume / Issue

  • 110 / 2

Start / End Page

  • 176 - 182

PubMed ID

  • 28859290

Pubmed Central ID

  • PMC6059138

Electronic International Standard Serial Number (EISSN)

  • 1460-2105

Digital Object Identifier (DOI)

  • 10.1093/jnci/djx135


  • eng

Conference Location

  • United States