Expression of estrogen receptor beta isoforms in pancreatic adenocarcinoma.

337Background: There have been several limited trials in which tamoxifen efficacy was tested in patients with pancreatic adenocarcinoma (PAC). Most of these studies were small series of patients with unresectable PAC and reported mixed results. In these studies, patients were not stratified by estrogen receptor status because estrogen receptor beta (ER-b) had not yet been identified, and PAC did not express the traditional ER-alpha. Recent studies showed that the effects of estrogens, phytoestrogens and tamoxifen on PAC cell lines depended on ER-b expression. The aim of this study was to investigate ER-b expression in human PAC and whether such expression correlates with any clinicopathologic parameters. Methods: Sections of tissue microarray containing 18 formalin fixed and paraffin embedded human PAC were stained by immunohistochemistry (IHC) using monoclonal antibodies to ER-b isoforms 1, 2, and 5 (ER-b1, ER-b2, and ER-b5, respectively), and for Cyclin A. The levels of ER-b isoform expression in tumor ...