Ethnicity and differences in mammary myoepithelial cell layers and inflammatory cell infiltration: Implications for differences in tumor development and behavior

Abstract

Objective:The incidence and clinical course of breast cancer vary significantly between Asian and Western females. Despite tremendous intervention efforts focused on tumor cells, the trend has remained unchanged during the past 30 years. This study attempted to examine the tumor surroundings that may contribute to the racial disparity. Methods: Tissue sections from 15 Western and 15 Asian females with similar breast tumors were compared for a panel of tumor suppressor‐ and inflammation‐related markers.Results:Compared to their Asian counterparts, Western females had the following unique features: [1] a significantly higher frequency of focal disruptions and lower tumor suppressor expression in myoepithelial (ME) cell layers, [2] significantly higher rate of leukocyte and mast cell infiltration.Conclusions:As the ME cell layer is the physical barrier to prevent tumor invasion, and chronic inflammation is a potential tumor promoter, these differences in tumor surroundings may contribute to the observed higher incidence and severity of breast cancer in Western women (Supported by grant 2006CB910505 from the Ministry of Chinese Science and Technology Department, and DAMD17‐01‐1‐0129, DAMD17‐01‐1‐0130, and PC051308 from US Congressionally Directed Medical Research Programs, and BCTR0706983 from The Susan G. Komen Breast Cancer Foundation).