Assessment of HER2 status from an epidemiology study in tumor tissue samples of gastric and gastro-esophageal junction cancer: Spanish results of the HER-EAGLE study.

4089 Background: Overexpression of HER2 is an important biomarker in gastroesophageal junction (GEJ) and gastric cancer (GC) and a predictive factor for trastuzumab (T, Herceptin). The ToGA phase III trial showed the benefit in overall survival of adding trastuzumab to chemotherapy inHER2-positive advanced GEJ/GC patients, following validated scoring criteria by a central laboratory. This study examines the incidence of HER2 positivity (local laboratories) in GEJ/GC according to EMA Herceptin label. Methods: HER-EAGLE was an epidemiological, non–interventional, international study assessing HER2 status by IHC/ISH in tumor samples from any stage GEJ/GC patients. Neutral buffered 10% formalin embedded tissues (surgical excision specimens or minimum 6-8 biopsies) analyzed via validated Ventana and Dako methods and scoring criteria used in ToGA: HER2-positive if IHC 3+ or IHC 2+ (FISH/SISH confirmed; HER2/CEP17 ratio ≥ 2.0); HER2-negative if IHC 0 or IHC 1+. Overall and subgroup estimates calculated with 95%C...