Real-Time Reverse Transcription-PCR Detects KS1/4 mRNA in Mediastinal Lymph Nodes from Patients with Non-Small Cell Lung Cancer

Abstract

Non-small cell lung cancer (NSCLC) is the most common cancer-related cause of death for both men and women in the US. Standard therapies for patients with NSCLC include surgery, chemotherapy, and radiation therapy, and the stage of disease dictates choice of therapy. The current staging system for lung cancer uses the American Joint Committee on Cancer TNM system, and its goal is to classify patients into groups based on the extent of disease. This system relies heavily on the pathologic evaluation of the primary tumor (T), regional nodes (N), and distant metastases (M). Patients in whom mediastinal lymph nodes (MLNs) are involved (N2 or N3) are classified with stage III disease (1) and are generally considered inoperable. The recent identification of genes overexpressed in lung cancer (2)(3)(4) combined with advances in real-time reverse transcription-PCR (RT-PCR) provide the opportunity to establish sensitive and specific ways to analyze MLNs. In addition, molecular biology approaches using real-time RT-PCR are well suited to the analysis of lymph node tissue procured through minimally invasive procedures such as endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA). This technique enables reliable biopsy of MLNs without the need for general anesthesia or surgery (5). Given the advantages of EUS-FNA, we investigated the possibility that metastatic disease could be reliably detected in MLNs of NSCLC patients by real-time RT-PCR. To define the ability of real-time RT-PCR to detect metastatic NSCLC in MLNs, we procured by EUS-FNA nine MLNs containing metastatic NSCLC (five adenocarcinomas, one large cell carcinoma, one squamous cell carcinoma, and two uncharacterized carcinomas). For negative controls, we collected 30 cervical lymph nodes obtained by surgical resection. Protocols for tissue procurement and patient consent governing all aspects of this study were reviewed and approved by the Medical University of South Carolina Institutional Review Board. For EUS-FNA, a …