677P - Survival Impact of HER2 Status in Patients with Gastric Cancer: a Multicenter Large-Scale Study in Japan

Abstract

ABSTRACT Background Although it has been proven in the ToGA study that HER2 expression is a predictive factor of trastuzumab treatment, the relation between HER2 status and prognosis in gastric cancer patients was still unknown. A multicenter large-scale study was conducted to evaluate the prognostic value of HER2 status in gastric cancer. Methods A total of 1152 cases with gastric cancer which was surgically resected between 2000 and 2006 were registered to this study. The neoadjuvant treatment cases were excluded. Tumors were centrally tested for HER2 status with immunohistochemistry (IHC) and fluorescence in-situ hybridization (FISH). HER2 expressions of resected tissues were evaluated according to the same criteria with the ToGA study. The relation between HER2 expression and clinicopathological factors was examined by Fisher's exact test. The hazard ratio (HR) for death in HER2-positive cases was estimated, and overall survivals (OS) were compared between HER2-positive and HER2-negative cases using log-rank test. Results The number of cases with IHC 0 / 1+ / 2+ / 3+ was 662 / 208 / 120 / 162, and eighteen of IHC 2+ cases showed FISH-positive. In total, the proportion of HER2-positive was 15.6% (180/1152). HER2-positive cases were more frequent in differentiated type tumors (P Conclusions HER2 expression is an independent factor of poor prognosis in resected gastric cancer, showing trends of higher HR in earlier stage. Disclosure All authors have declared no conflicts of interest.