Validation of Intra-operative Detection of Paratracheal Lymph Node Metastasis Using Real-time RT–PCR Targeting Esophageal Squamous Cell Carcinoma

Background: We previously reported that there was a significant correlation between paratracheal lymph node (LN) metastasis and cervical LN metastasis in thoracic esophageal squamous cell carcinoma (ESCC) patients. The purpose of this study was to establish an intra-operative detection method of LN micrometastasis (MM) of ESCC using hematoxylin–eosin (HE) staining, immunohistochemistry (IHC) and real-time RT–PCR with a Light Cycler technique, and to evaluate which method, or combination of methods, is most suitable for intra-operative detection of paratracheal LN MM. Methods: Under informed consent, we obtained 33 dissected paratracheal LN samples from 22 operative patients with ESCC. Afterwards, one LN was separated into three parts by a sharp razor, and each part was checked for metastasis by HE staining, IHC with anti-cytokeratin antibody and real-time RT–PCR for SCC mRNA with a Light Cycler. Results: It took 3 h for detection by real-time RT–PCR, while it took 2 h by IHC. The detection rates of MM by HE staining, IHC and real-time RT–PCR were 50.0, 33.3 and 83.3%, respectively. However, there was a case of false negative detection that was not detected by IHC or PCR. Conclusion: The real-time RT–PCR method was useful for intra-operative detection of paratracheal LN metastasis. However, combination analysis of HE staining, IHC and real-time RT–PCR may be desirable because there was a case of false negative detection by IHC and real-time RT–PCR.