[646] Characterization of HER2 Expression in Primary Gastroesophageal Adenocarcinomas.

Jennifer A Jeung, Roshan Patel, Lizette Vila, Dara Wakefield, Chen Liu. University of Florida, Gainesville

Background: Overexpression of human epidermal growth factor receptor 2 (HER2) protein, a 185 kDa transmembrane tyrosine kinase receptor, has been detected in various solid tumors. Few studies have demonstrated that HER2 may also be overexpressed in gastroesophageal (GE) adenocarcinomas; however, the clinical significance of HER2 amplification in these tumors remains unclear. Targeted therapy with monoclonal antibody trastuzumab (Herceptin) may potentially be effective in the treatment of HER2 positive GE adenocarcinomas. The aim of our study was to quantify HER2 overexpression in GE adenocarcinomas by both visual and computer software analysis and correlate these findings with histopathologic features of GE adenocarcinomas.
Design: We identified 122 cases of primary gastric and esophageal adenocarcinomas received from 2004-2009. HER2 immunohistochemistry (IHC) was performed on paraffin sections. A visual and computer based analysis (ChromaVision analyzer) was used to quantitate HER2 expression and graded according to Hofmann's proposed HER2 IHC scoring system for gastric cancer. Parameters including TNM staging (AJCC/UICC convention) for resection specimens and histologic grade for resection and biopsy specimens were recorded and correlated with HER2 IHC.
Results: HER2 IHC results are demonstrated in Figure 1. Overall, 12% of GE adenocarcinomas were strongly positive (3+) for HER2, 10% were equivocal (2+), and 78% were weak to negative (18% were 1+ and 60% were 0). To date, 16 cases analyzed via image analysis demonstrated 94% concordance between the IHC score and digital interpretation. Of note, 86% of poorly differentiated (Grade 3) tumors and all tumors stage IIB and above were negative for HER2 IHC.

Conclusions: Only a subset of GE adenocarcinomas were found to strongly overexpress HER2. The majority of the poorly differentiated tumors or higher stage tumors appear to be negative for HER2 expression.
Category: Gastrointestinal

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 93, Monday Morning


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