Abstract
In the present study, the human orthologue of the secreted Xenopus laevis anterior gradient 2 (AGR2) protein was evaluated as a potential serum biomarker of lung adenocarcinoma. AGR2 protein levels were preoperatively measured in the serum of 111 primary lung adenocarcinoma patients and in 46 non-cancer controls with subsequent calculation of sensitivity and specificity in comparison with serum CEA levels. Correlations with clinicopathological variables were also assessed and survival analyses were performed according to the Kaplan-Meier method and differences determined with the log-rank test. The mean serum AGR2 level of lung adenocarcinoma patients in each stage, even Stage I, was significantly higher than in non-cancer controls (P < 0.001 for all stages, Mann-Whitney U test). The sensitivity was 65.8% (52.9% for stage IA), even higher than that of CEA, which was 45.0% (29.4% for stage IA), and the specificity was 87.0% according to the ROC curve (AUC=0.858). Positive serum AGR2 expression was significantly associated with the incidence of recurrence after surgery (P=0.025) and with a poor prognosis (P=0.037 for overall survival and P=0.004 for disease-free survival). Preoperative serum AGR2 might become a clinically useful biomarker for early detection, prediction of recurrence and prognosis with lung adenocarcinomas.