In this project we propose to construct Tissue Microarrays (TMAs) using both neoplastic and non-neoplastic tissues collected from the ongoing Polish Breast Cancer case-control study. Using the TMAs as a resource, we will examine the association of heterogeneous risk factors of breast cancer with the expression patterns and genetic polymorphisms of multiple markers that have been implicated in breast carcinogenesis and progression. Specifically, we will conduct a study exploring the relationship between expression patterns of key enzymes of hormonal metabolism and receptors to demonstrate the potential of this approach for studying the hormonal etiology of breast cancer.