Background: 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 investi?gate the clinical and prognostic efects of IGFBP?3 on ESCC.Methods: IGFBP?3 was detected by immunohistochemistry in parain?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?of scores for tumor positivity and to evaluate patient survival status. The χ2 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.Results: The threshold for IGFBP?3 positivity was set to greater than 65% [area under the ROC curve(AUC)(45.7%) were deined as having high IGFBP?3 expression= 0.690, P < 0.019]. Of the 70 ESCC patient tissues tested, 32. 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 classiication(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).Conclusions: 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. Background: 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 investi? Gate the clinical and prognostic efects of IGFBP 3 on ESCC. Methods: IGFBP 3 was detected by immunohistochemistry in parain 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 The χ2 test was performed to analyze the association of IGFBP 3 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. Results: The t hreshold for IGFBP-3 positivity was set to greater than 65% of the area under the ROC curve (AUC) (45.7%) were deined as having high IGFBP3 expression = 0.690, P <0.019]. , 32. 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 classi? Cation (P & lt; 0.05 for T, N, and M categories and clinical stages. Patients with elevated protein level of IGFBP-3 in the tumor had an improved radiotherapy response and prolonged overall survival (P <0.001). Conclusions: 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.