Prognostic significance of Human epidermal growth factor receptor-2 expression in patients with resectable gastric adenocarcinoma

Background: The purpose of this study was to investigate the correlation between human epidermal growth factor receptor 2 (HER2) overexpression and clinicopathologic factors and overall survival rate in patients who underwent curative gastrectomy for gastric adenocarcinoma. Methods: Among patients who underwent curative gastrectomy for gastric adenocarcinoma at Inje University Paik Hospital from January 2012 to December 2015, 782 patients underwent an immunohistochemical analysis to evaluate HER2 expression levels. Clinicopathologic records that were collected from a gastric cancer database were retrospectively reviewed to identify clinicopathologic factors and survival rates of the patients. Results: HER2 overexpression was detected in 166 patients (21.2%). There was a statistically significant correlation between HER2 expression level and sex (p = 0.013), histologic differentiation (p < 0.001), Lauren classification (p < 0.001), and T pathologic stage (p = 0.022). There were no statistically significant relationships between HER2 expression level and overall 5-year survival rate (p = 0.775) and overall 5-year survival rate of gastric adenocarcinoma classified according to the TNM stage (stage I: p = 0.756, stage II: p = 0.571, stage III: p = 0.704). The HER2 expression level was not affected by the overall 5-year survival rate in the uni- and multivariate analyses. Conclusions: In this study, the HER2 overexpression rate in gastric adenocarcinoma was 21.2% and was observed in well- and moderately differentiated types according to histologic differentiation, intestinal type according to the Lauren classification, male, and low T stage. There was no correlation between HER2 expression level and overall 5-year survival rate, and HER2 expression level was not associated with independent prognostic factors.