Significance of GSTP1 for predicting the prognosis and chemotherapeutic efficacy in esophageal squamous cell carcinoma

Abstract

Glutathione S-transferases (GSTs) have been reported to be activated in several types of cancers, including esophageal squamous cell carcinoma (ESCC). The aim of the present study was to investigate whether GSTP1 protein expression is a useful predictor of the clinical outcome or drug resistance in ESCC. Immunohistochemistry was conducted with 75 ESCC resected specimens using a monoclonal antibody against GSTP1. The patients were divided into two groups according to the degree of GSTP1 staining, and the relationship between the GSTP1 level and the clinicopathological features was examined. Seventy-five patients were divided into low (grade 1, n=36) and high (grade 2, n=39) GSTP1 expression groups. The overall survival was significantly worse in the grade 2 patients than in the grade 1 patients (5-year survival rate, 78.5 vs. 51.2%; p=0.027). Cox proportional hazard analysis revealed that macroscopic type 3 or 4 disease (p=0.001), lymph node metastasis (p=0.010), and high GSTP1 expression (p=0.029) were independent predictors of a poor prognosis. With regard to the subgroup analysis among the 31 patients undergoing adjuvant chemotherapy, the grade 2 patients had a worse prognosis than did the grade 1 patients (5-year survival rate, 45.0 vs. 81.8%; p=0.081). This tendency was not observed in the subgroup without adjuvant chemotherapy (5-year survival rate, 51.7 vs. 59.9%; p=0.979). In conclusion, the GSTP1 expression is a good predictor of prognosis, and it may be closely related to the chemotherapeutic efficacy of 5-FU plus cisplatin in ESCC patients.