Molecular Breast Cancer Subtypes in Premenopausal and Postmenopausal African-American Women: Age-Specific Prevalence and Survival

Background Breast cancer is currently regarded as a heterogeneous disease classified into various molecular subtypes using gene expression analysis. These molecular subtypes include: basal cell-like, Her-2/neu, luminal A, and luminal B. Objectives To analyze the prevalence and clinicopathologic associations for molecular breast cancer subtypes in premenopausal and postmenopausal African-American women. Design A retrospective analysis of all African-American women diagnosed with breast cancer from 1998 to 2005, who had assessable data for ER, PR, and Her-2/neu status. Molecular subtype classification was done based on immunohistochemical surrogates for ER, PR, and Her-2/neu status obtained from Howard University tumor registry for each patient. The molecular subtypes were defined as: luminal A (ER+ and/or PR+, HER2−), luminal B (ER+ and/or PR+, HER2+), basal-like (ER−, PR−, HER2−), and Her-2/neu (ER−, PR−, and HER2+). Outcome Measures We analyzed the prevalence of molecular breast cancer subtypes in a population of African-American women and determined their associations with patient demographics and clinicopathologic variables: node status, tumor size, histological grade, p53 mutation status, and breast cancer-specific survival. Results The luminal A subtype was the most prevalent in our study sample (55.4%) compared with (11.8%) luminal B, (21.2%) basal cell-like, and (11.6%) Her-2/neu subtypes. The molecular subtypes did not differ by menopausal status. However, when stratified into age-specific groups, the basal cell-like subtype (57.1%) was the most prevalent in the age group