LAUSR

Background Over-expression of inhibitor of differentiation or DNA binding 1 (Id-1) is associated with poor prognosis in esophageal squamous cell carcinoma (ESCC). However, some biomarkers discordant expression in metastasis has been reported previously. We aimed to confirm possible differential expression and prognostic value of Id-1 in paired metastatic lymph node (PMLN). Methods Expression of Id-1 in primary tumors (PT) and paired regional metastatic lymph nodes of ESCC were evaluated with immunohistochemical (IHC) analysis. Statistical analysis of Kaplan-Meier method was performed to test the prognostic significance of Id-1 expression. Results The expression of Id-1 was down-regulated in metastatic lymph nodes compared with primary esophageal tumors (P<0.001). Patients with 1 to 2 lymph nodes involved had significantly higher Id-1 expression in metastatic lymph nodes (P=0.028). The similar association was observed between a ratio of involved to examined lymph nodes ≤0.2 and high level Id-1 expression in lymphatic metastases (P=0.011). Better overall survival with statistical significance was observed in patients with higher level Id-1 expression in metastatic lymph nodes (P=0.015). The results of Id-1 expression in metastatic lymph node and paired PT was to predict prognosis effective in out cohort (P=0.035). Conclusions The level of Id-1 protein expression was down-regulated from PT to metastatic lymph node. It was contrary to previous studies that strong expression of Id-1 in metastatic lymph nodes was associated with better clinical outcomes in patients with stage T3N1-3M0 ESCC.