Carolina Dominguez1, Marilin Rosa2, Taara B George3, Jose Pimiento4, Gregory Y Lauwers2, Domenico Coppola5. 1. Department of Pathology and Laboratory Medicine, University of South Florida, Tampa, FL, U.S.A. 2. Department of Anatomic Pathology, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, U.S.A. 3. Department of Arts and Science, University of South Florida, Tampa, FL, U.S.A. 4. Department of Gastrointestinal Oncology, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, U.S.A. 5. Department of Anatomic Pathology, H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL, U.S.A. domenico.coppola@moffitt.org.
Abstract
BACKGROUND/AIM: Trastuzumab® is used for human epidermal growth factor receptor 2 (HER2)-overexpressing metastatic gastric/gastroesophageal junction (GEJ) adenocarcinoma. Our aim was to compare HER2 expression by immunohistochemistry (IHC) and dual in situ hybridization (DISH) in early-stage vs. late-stage gastric and GEJ tumors. MATERIALS AND METHODS: Fifty early-stage and 50 late-stage gastric tumors and a similar number of early-stage and late-stage GEJ tumors were studied. HER2 was analyzed by IHC and dual-ISH using tissue microarray. RESULTS: Of 200 selected cases, 168 had satisfactory results. Among the 110 cases with both tests successfully performed, there were only five cases with discrepancy between assays (4.5%). Seven equivocal (2+) cases by IHC were all found to be amplified by dual-ISH. When compared with IHC, dual-ISH identified 12 additional HER2-positive cases (10.9%). CONCLUSION: The 12.5% overall overexpression/amplification in gastric and GEJ adenocarcinomas is in concordance with previous reports. No correlation was found between tumor stage and HER2 overexpression/amplification. Determination of HER2 in limited tissue samples benefits from combinational IHC and ISH testing. Copyright
BACKGROUND/AIM: Trastuzumab® is used for human epidermal growth factor receptor 2 (HER2)-overexpressing metastatic gastric/gastroesophageal junction (GEJ) adenocarcinoma. Our aim was to compare HER2 expression by immunohistochemistry (IHC) and dual in situ hybridization (DISH) in early-stage vs. late-stage gastric and GEJ tumors. MATERIALS AND METHODS: Fifty early-stage and 50 late-stage gastric tumors and a similar number of early-stage and late-stage GEJ tumors were studied. HER2 was analyzed by IHC and dual-ISH using tissue microarray. RESULTS: Of 200 selected cases, 168 had satisfactory results. Among the 110 cases with both tests successfully performed, there were only five cases with discrepancy between assays (4.5%). Seven equivocal (2+) cases by IHC were all found to be amplified by dual-ISH. When compared with IHC, dual-ISH identified 12 additional HER2-positive cases (10.9%). CONCLUSION: The 12.5% overall overexpression/amplification in gastric and GEJ adenocarcinomas is in concordance with previous reports. No correlation was found between tumor stage and HER2 overexpression/amplification. Determination of HER2 in limited tissue samples benefits from combinational IHC and ISH testing. Copyright