Prognostic impact of HER2, EGFR, and c-MET status on overall survival of advanced gastric cancer patients

Abstract

This study was conducted to investigate whether human epidermal growth factor receptor 2 (HER2) status, epidermal growth factor receptor (EGFR) status, and c-MET status are independent prognostic factors for advanced gastric cancer patients who received standard chemotherapy. Unresectable or recurrent gastric or gastroesophageal junction cancer patients with histologically confirmed adenocarcinoma treated with S-1 plus cisplatin as first-line chemotherapy were eligible. Formalin-fixed paraffin-embedded tumor samples were examined for HER2, EGFR, and c-MET status using immunohistochemistry (IHC). Additionally, gene amplification was examined using fluorescent in situ hybridization (FISH) for HER2. Positivity was defined as an IHC score of 3+ or an IHC score of 2+/FISH positive for HER2, and an IHC score of 2+ or 3+ for both EGFR and c-MET. Of the 293 patients from nine institutions, 43 (15%) were HER2 positive, 79 (27%) were EGFR positive, and 120 (41%) were c-MET positive. Ten patients (3%) showed positive co-expression of HER2, EGFR, and c-MET. After a median follow-up time of 58.4 months with 280 deaths, there was no significant difference in overall survival (OS) in terms of HER2 and EGFR status. However, there was a significant difference in OS between c-MET-positive and c-MET-negative patients [median, 11.9 months vs 14.2 months; hazard ratio, 1.31 (95% confidence interval, 1.03-1.67); log-rank P = 0.024]. Multivariate analysis also showed that c-MET positivity was still a prognostic factor for OS [hazard ratio, 1.30 (95% confidence interval, 1.02-1.67); P = 0.037]. The study suggested that c-MET-positive status had poor prognostic value. These data could be used as the basis for future clinical trials for targeting agents for advanced gastric cancer patients.