Breast Cancer Research and Treatment

, Volume 144, Issue 3, pp 689–699

Race and breast cancer survival by intrinsic subtype based on PAM50 gene expression

Authors

    • Division of ResearchKaiser Permanente Northern California
  • Carol Sweeney
    • Division of EpidemiologyUniversity of Utah
  • Marilyn L. Kwan
    • Division of ResearchKaiser Permanente Northern California
  • Charles P. Quesenberry
    • Division of ResearchKaiser Permanente Northern California
  • Erin K. Weltzien
    • Division of ResearchKaiser Permanente Northern California
  • Laurel A. Habel
    • Division of ResearchKaiser Permanente Northern California
  • Adrienne Castillo
    • Division of ResearchKaiser Permanente Northern California
  • Phillip S. Bernard
    • Division of EpidemiologyUniversity of Utah
  • Rachel E. Factor
    • Division of EpidemiologyUniversity of Utah
  • Lawrence H. Kushi
    • Division of ResearchKaiser Permanente Northern California
  • Bette J. Caan
    • Division of ResearchKaiser Permanente Northern California
Epidemiology

DOI: 10.1007/s10549-014-2899-5

Cite this article as:
Kroenke, C.H., Sweeney, C., Kwan, M.L. et al. Breast Cancer Res Treat (2014) 144: 689. doi:10.1007/s10549-014-2899-5

Abstract

To evaluate whether differences in PAM50 breast cancer (BC) intrinsic (Luminal A, Luminal B, Basal-like, and HER2-enriched) subtypes help explain the Black–White BC survival disparity. Utilizing a stratified case-cohort design, this study included 1,635 women from the Pathways and Life After Cancer Epidemiology cohorts, selecting women with tumors based upon IHC classification, recurrences, and deaths.One millimeter punches were obtained from tumor tissue, and expression of the PAM50 genes for molecular subtype was determined by RT-qPCR of extracted RNA. Cox proportional hazards models were used to analyze associations between race and BC outcomes, adjusted for PAM50 BC subtype. All tests of statistical significance were two-sided. Black women had a higher prevalence of the Basal-like BC subtype. Adjusted for potential confounding variables and disease characteristics at diagnosis, Black women had higher risks of recurrence (HR 1.65, 95 % CI 1.06–2.57) and breast cancer-specific mortality (HR 1.71, 95 % CI 1.02–2.86) than White women, but adjusting further for subtype did not attenuate survival disparities. By contrast, Hispanic women had a lower risk of recurrence (HR 0.54, 95 % CI 0.30–0.96) than Whites. Among those with the Basal-like subtype, Black women had a similar recurrence risk as women in other race groups but a higher recurrence risk for all other subtypes. Hispanic women had a lower recurrence risk within each subtype, though associations were not significant, given limited power. Although Black women had a higher risk of the Basal-like subtype, which has poor prognosis, this did not explain the Black–White BC survival disparity.

Keywords

RaceEthnicityBreast cancer survivalBreast cancer mortalityGene expressionMolecular subtypeIntrinsic subtypePAM50

Copyright information

© Springer Science+Business Media New York 2014