Expression and prognostic relevance of Id1 in stage III esophageal squamous cell carcinoma

Inhibitor of differentiation 1 (Id1) plays a role in cellular differentiation, proliferation, angiogenesis and tumor invasion. In current study, we investigated the expression of Id1 protein in 189 specimens of stage III ESCC by immunohistochemistry. The correlation between Id1 expression and clinicopathological parameters in terms of gender, age, tumor location, differentiation, pathological T stage and pathological N stage was also explored. Immunohistochemical staining showed that Id1 was expressed in all cases (100%). According to ROC curve, we selected 6.33 as the cutoff score. There were 95 cases in high expression group (> 6.33) and 94 cases in low expression group (⩽ 6.33) respectively. The Id1 expression was associated negatively with differentiation, and positively with pathological N stage (P< 0.05, bothly); No significant correlation was observed between Id1 expression and gender, age, tumor location or pathological T stage (P> 0.05). As shown by the Kaplan-Meier curve, the overall survival rate of high expression group was significantly lower than that of low expression group (P< 0.001). The expression of Id1 protein has a close relationship with differentiation degree, pathological N stage and survival in ESCC patients. Id1 could be considered as a prognostic predictor for stage III ESCC patients.