Prognostic significance and frequency of EGFR expression and amplification in surgically resected advanced gastric cancer

Abstract

Objective: The aim of this study is to find the frequency and the role of epidermal growth factor receptor expression as a prognostic biomarker in gastric cancer. Methods: We evaluated the prognostic value and frequency of epidermal growth factor receptor expression and amplification using immunohistochemistry and silver in situ hybridization in a large cohort of curatively resected gastric cancer. Results: Of the total of 935 cases, 294 (31.4%), 101 (10.8%) and 36 (3.9%) patients showed epidermal growth factor receptor 1+, 2+ and 3+ expression on immunohistochemistry, respectively. Epidermal growth factor receptor-positive (2+/3+) patients more frequently had intestinal type than epidermal growth factor receptor-negative (0/1+) patients (82.5 vs. 44.1%, P < 0.001). After adjusting for sex, age, stage and adjuvant chemotherapy, epidermal growth factor receptor-positive patients had a favorable overall survival outcome compared with epidermal growth factor receptor-negative patients (hazard ratio, 0.734; 95% confidence interval, 0.541-0.997; P = 0.047), especially in Stage III disease (hazard ratio, 0.676; 95% confidence interval, 0.472-0.968; P = 0.033). Among the 393 cases available for in situ hybridization, the correlation between immunohistochemistry and in situ hybridization was statistically significant (P = 0.001). Thirteen patients with gene amplification (3.3%) did not show different survival outcome with others (P = 0.359). Conclusion: Epidermal growth factor receptor positivity was an independent favorable prognostic factor for gastric cancer, especially in Stage III disease.