Breast cancer incidence according to age, race, and hormone receptor subtype: A SEER database analysis.

Abstract

e13059 Background: While incidence rates of breast cancer have been shown to vary based on age and race, hormone receptor (HR) subtype is an important prognostic indicator and it is unclear to what extent HR subtype varies across age and race. Identifying breast cancer at an early stage, especially in the more aggressive subtypes, correlates with improved overall outcomes. In this study we sought to examine the distribution age, race, within HR subtype in women diagnosed with incident breast cancer. Methods: Data from the SEER registry, years 2010-2013, was queried to produce race stratified age distributions of incident cases of invasive female breast cancer according to HR subtype: Her2+/HR+ (n = 21288), Her2+/HR- (n = 9325), Her2-/HR+ (n = 153130), Her2-/HR- (n = 24455). Race was categorized as White, Black, and Other. Mantel-Haenszel Chi-Square (χ2MH) test was used to determine whether racial variations across the age categories (20-44 years, 45-64 years, and 65+ years) were the same across hormone receptor subtypes. Results: Across all HR subtypes and race categories, incident breast cancer burden was highest among women aged 45-64 years (p < 0.001). Age distribution differed significantly across HR subtypes (p < 0.001). Variations across age distributions and race differed by HR subtypes (p < 0.001). When the incident burden for younger Black women (aged ≤ 44 years) to Black women aged 45-64 years was compared to the same age categories for White women, it was found that variations across the racial and age groups were different across HR subtypes (p < 0.001). These results would suggest a significant three-way interaction between age, race, and HR subtype. Conclusions: There are significant differences in breast cancer incidence according to age, race, and HR subtype. Further investigation into a mortality effect is necessary to determine breast cancer screening strategies when these variables are taken into consideration.