The impact of HER2 positivity on survival in metastatic gastric and GEJ cancer in the province of British Columbia: An updated analysis.

Abstract

e14568 Background: HER2 positive gastric (GC) and GEJ adenocarcinoma has been associated with a worse survival outcome. This study examines the survival rate of patients with metastatic HER2 positive GC and GEJ adenocarcinomas in the province of BC. Methods: Formalin fixed embedded tissue from patients (pts) with resected gastric or GEJ adenocarcinoma from 2004-2011 were identified retrospectively through the BC Cancer Agency registry and prospectively for pts with a new diagnosis of advanced disease. Biopsies and resection samples were analyzed via previously validated methods. IHC scores of 3 were considered positive (+), 2 were equivocal and 0 or 1 were negative (-). A 10% cut-off was used to determine positive samples. Equivocal staining was considered positive via FISH or SISH with a ratio of > 2.2 considered amplified. Patient characteristics were abstracted to an anonymized database. Kaplan-Meier curves were calculated to evaluate overall survival from time of diagnosis or relapse to death for pts with HER2 + or - disease. Results: 179 of 304 pts were identified with metastatic or relapsed gastric or GEJ adenocarcinoma without Traztumumab treatment. 21 (12%) pts were HER2 + either by IHC, FISH or SISH. Refer to the table for characteristics of both groups. Median survival was not significantly different among HER2 + and - pts (4.0 mo vs. 7.3 mo, p=0.089). Conclusions: The rate of HER2 positivity is similar to that seen in trial data. HER2 positivity trends to a worse prognosis but was not significant in this study. [Table: see text]