COMPARISON OF BIOCHEMICAL AROMATASE-ACTIVITY WITH AROMATASE IMMUNOHISTOCHEMISTRY IN HUMAN BREAST CARCINOMAS

The role of intratumoural aromatase in human breast cancer growth rema ins controversial. At the same time as the use of aromatase inhibitors in the clinical setting continues to increase, so does the need for a tool to predict the likely response to this treatment. Intratumoural aromatase is a candidate predictive marker. The presently accepted 'go ld standard' methods of assessment of aromatase activity are biochemic al assays. However, these are time-consuming and require relatively la rge amounts of fresh or frozen tissue which are frequently not availab le. The development of a reliable immunohistochemical technique for th e assessment of intratumoural aromatase which could be applied rapidly to more readily available paraffin-embedded material is therefore hig hly desirable. Unfortunately aromatase immunohistochemistry is also an area of controversy; some authors describe localisation to the stroma l compartment but others to the malignant epithelial cells themselves. The aim of this study was therefore to compare immunohistochemical sc ores using two different antibodies with biochemical aromatase activit y. Taking a group of 29 human breast carcinomas we demonstrated a stro ng correlation between immunoreactivity with a monoclonal antibody (p = 0.01) but not with a polyclonal (p = 0.16). The monoclonal produced reactivity in both epithelial and stromal cells but the polyclonal in only stromal cells. The implications of these results are discussed to gether with the need for further studies.