ABSTRACT
<p><b>BACKGROUND</b>Insulin-like growth factor-binding protein-3 (IGFBP-3) is suggested to predict the radiosensitivity and/or prognosis of patients with esophageal squamous cell carcinoma (ESCC). The present study was designed to investigate the clinical and prognostic effects of IGFBP-3 on ESCC.</p><p><b>METHODS</b>IGFBP-3 was detected by immunohistochemistry in paraffin-embedded tissues from 70 ESCC patients treated with radiotherapy alone and further examined by western blotting analysis in 10 pairs of fresh ESCC tissues and adjacent non-malignant esophageal specimens. Receiver operating characteristic (ROC) analysis was used to determine cut-off scores for tumor positivity and to evaluate patient survival status. The χ(2) test was performed to analyze the association of IGFBP-3 expression with clinical characteristics and radiotherapy response. Associations between prognostic outcomes and IGFBP-3 expression were investigated using Kaplan-Meier analysis and the Cox proportional hazards model.</p><p><b>RESULTS</b>The threshold for IGFBP-3 positivity was set to greater than 65% [area under the ROC curve (AUC)=0.690, P<0.019]. Of the 70 ESCC patient tissues tested, 32 (45.7%) were defined as having high IGFBP-3 expression. The levels of IGFBP-3 protein expression were decreased in 70.0% (7 of 10) of ESCC tissues compared with adjacent non-malignant esophageal tissue. In addition, IGFBP-3 expression was associated with pathologic classification (P<0.05 for T, N, and M categories and clinical stage). Patients with elevated protein level of IGFBP-3 in the tumor had an improved radiotherapy response and prolonged overall survival (P<0.001).</p><p><b>CONCLUSIONS</b>High level of IGFBP-3 expression in ESCC associates with early clinical stages and are predictive for favorable survival of the patients treated with radiotherapy.</p>