The aim of the study was to determine
epidermal growth factor receptor (EGFR) expression in gastric
adenocarcinoma by standardized immunohistochemistry and to correlate EGFR expression with clinical features and patient survival. EGFR expression was investigated in
paraffin sections of resection specimens of 89 gastric
carcinomas from Mexican Mestizo patients using standardized immunohistochemistry with
antigen retrieval (Dako EGFRpharmDx assay detection system). Membrane staining of EGFR was evaluated in the neoplastic cells and graded using a semiquantitative score (0-3+). Of the 89
carcinomas examined, staining of neoplastic cells was weak in 17 (19.1%, score 1+), moderate in 16 (18.0%, score 2+), and strong in nine cases (10.1%, score 3+). EGFR reactivity was heterogeneous, frequently showing completely negative up to 3+ positive areas within an individual
tumor. EGFR reactivity score correlated with distant
metastases (P=0.002) and clinical stage (P=0.033). EGFR score 0/1+ was significantly associated with an increase in patient survival when compared to score 2+/3+ (P=0.0006). In a multivariate analysis, EGFR positive cells in muscularis or subserosa (P=0.004), distant
metastases (P=0.016) and residual disease (P=0.039) were significantly correlated with decreased survival. The prognosis was associated with the EGFR reactivity score (P=0.003), distant
metastases (P=0.0001) and residual disease (P=0.012) in a univariate analysis. EGFR reactivity in neoplastic cells is an independent prognostic factor in gastric
adenocarcinoma. The relevance of the heterogeneity in EGFR expression with regard to
tumor progression,
metastasis and anti-EGFR
therapy needs to be studied.