Lung cancer lymph node micrometastasis detection using real-time polymerase chain reaction: Correlation with vascular endothelial growth factor expression

Objectives: Lymph node staging provides critical information in patients with non-small cell lung cancer (NSCLC). Lymphangiogenesis may be an important contributor to the pathophysiology of lymphatic metastases. We hypothesized that the presence of lymph node micrometastases positively correlates with vascular endothelial growth factors (VEGFs) A, C, and D as well as VEGF-receptor-3 (lymphangiogenic factors) expression in lymph nodes. Methods: Forty patients with NSCLC underwent preoperative positron emission tomography-computed tomography and mediastinoscopy. Real-time polymerase chain reaction (RT-PCR) assays for messenger RNA expression of epithelial markers (ie, cytokeratin 7; carcinoembryonic antigen-related cell adhesion molecule 5; and palate, lung, and nasal epithelium carcinoma-associated protein) were performed in selected fluorodeoxyglucose-avid lymph nodes. VEGF-A, VEGF-C, VEGF-D, and VEGF receptor-3 expression levels were measured in primary tumors and lymph nodes. Wilcoxon rank sum test was run for the association between the RT-PCR epithelial marker levels and VEGF expression levels in the lymph nodes. Results: RT-PCR for cytokeratin 7; carcinoembryonic antigen-related cell adhesion molecule 5; or palate, lung, and nasal epithelium carcinoma-associated protein indicated lymph node micrometastatic disease in 19 of 35 patients (54%). There was a high correlation between detection of micrometastases and VEGF-A, VEGF-C, VEGF-D, or VEGF receptor-3 expression levels in lymph nodes. Median follow-up was 12.6 months. Conclusions: RT-PCR analysis of fluorodeoxyglucose-avid lymph nodes results in up-staging a patient's cancer. Micrometastases correlate with the expression of VEGF in lymph nodes in patients with NSCLC. This may reflect the role of lymphangiogenesis in promoting metastases.