Prognostic relevance of Id-1 expression in patients with resectable esophageal squamous cell carcinoma

Inhibitor of differentiation or DNA binding 1 (Id-1) is a transcriptional regulator that is associated with enhanced malignant potential and unfavorable survival in many cancers. However, its role and clinical significance in resectable esophageal squamous cell carcinoma (ESCC) has not been elucidated adequately. The purpose of this study was to explore the pattern of Id-1 expression and analyze its correlation with clinical outcomes of patients with resectable ESCC.

Primary tumors from 407 surgically resected ESCC specimens assembled on tissue microarrays were evaluated with immunohistochemical analysis for Id-1. The effect of Id-1 expression on survival outcome was analyzed by the Kaplan-Meier method.

The expression of Id-1 correlated closely with pT category (p<0.001), pathologic staging (p<0.001), and pN category (p<0.001). The sensitivity, specificity, and accuracy of predicting lymph node metastasis by Id-1 expression were 93.3%, 94.7%, and 94.1%, respectively. Disease-specific survival was significantly favorable in patients with low-level Id-1 expression (p<0.001). Overexpression of Id-1 was also effective to predict unfavorable survival in subgroups of patients with poor differentiation (p<0.001) or with advanced T staging (p<0.001). Multivariate analysis showed that the level of Id-1 expression was an independent prognostic factor in ESCC (p<0.001; relative risk, 1.578).

Expression of Id-1 can be used as a complement for predicting lymph node metastasis in pretreatment workup. High level of Id-1 expression suggested unfavorable prognosis for patients with resectable ESCC.