Citation
Troester, Melissa A.; Sun, Xuezheng; Allott, Emma H.; Geradts, Joseph; Cohen, Stephanie M.; Tse, Chiu-Kit J.; Kirk, Erin L.; Thorne, Leigh B.; Mathews, Michelle M.; & Li, Yan, et al. (2018). Racial Differences in PAM50 Subtypes in the Carolina Breast Cancer Study. Journal of the National Cancer Institute, 110(2), djx135. PMCID: PMC6059138Abstract
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.
URL
http://dx.doi.org/10.1093/jnci/djx135Reference Type
Journal ArticleYear Published
2018Journal Title
Journal of the National Cancer InstituteAuthor(s)
Troester, Melissa A.Sun, Xuezheng
Allott, Emma H.
Geradts, Joseph
Cohen, Stephanie M.
Tse, Chiu-Kit J.
Kirk, Erin L.
Thorne, Leigh B.
Mathews, Michelle M.
Li, Yan
Hu, Zhiyuan
Robinson, Whitney R.
Hoadley, Katherine A.
Olopade, Olufunmilayo I.
Reeder-Hayes, Katherine E.
Earp, H. Shelton
Olshan, Andrew F.
Carey, Lisa A.
Perou, Charles M.