Race And Age Differences In Pam50 Biomarker Status In The Carolina Breast Cancer Study

Background: African American breast cancer patients have lower relative frequency of hormone receptor (HR)-positive/HER2-negative disease and higher subtype-specific mortality. However, few population-based studies have RNA-based subtyping data, and racial differences in the biology of HR-positive/HER2-negative tumors are not well understood. Methods: Using data and biospecimens from the Carolina Breast Cancer Study (CBCS) Phase 3 (2008-2013), we classified approximately 1,000 invasive breast cancers according to PAM50 subtype and two risk of recurrence scores (ROR-P and ROR-PT). Relative frequency of Luminal A, Luminal B, Her2-enriched, and Basal-like subtypes and ROR scores (low/medium/high) were compared by race (blacks vs. whites) and age (≤50 years vs. u003e50 years), overall and among HR-positive/HER2-negative cases. Results: Black women of all ages had significantly higher relative frequency of Basal-like breast cancer (36 and 31% in blacks vs. 18 and 15% in whites; younger and older, respectively) and lower frequency of Luminal A breast cancer (26 and 34% in blacks vs. 43 and 52% in whites; younger and older, respectively). Frequency of Luminal B and HER2-enriched breast cancer did not vary by race or age. Among clinically HR-positive, HER2-negative cases, Luminal A subtype comprised only half of the cases among black women, and was significantly less common than among white women (51% vs 60% in whites, p Conclusions: Multi-gene assays highlight disparities in frequency of aggressive, poorer prognosis tumor subtypes and implicate differences in tumor biology as an important contributor to mortality disparities among HR-positive/HER2-negative patients. Citation Format: Troester MA, Sun X, Allott EH, Kit C-K, Thorne L, Mathews M, Cohen SM, Geradts J, Kirk E, Li Y, Hu Z, Robinson W, Hoadley KA, Reeder-Hayes K, Earp S, Olshan AF, Carey LA, Perou CM. Race and age differences in PAM50 biomarker status in the Carolina breast cancer study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD8-01.