Detection of lymph node micrometastasis in esophageal carcinoma

The presence of lymph node metastasis is the most important prognostic factor in esophageal squamous cell carcinoma. Molecular biology techniques have improved the ability to recognize micrometastasis in lymph nodes, bone marrow, and peripheral blood. Previous studies have demonstrated that cytokeratin 19 reverse transcriptasepolymerase chain reaction can detect tumor cells even when lymph nodes appear normal histologically. However, the presence of pseudogenes for cytokeratin 19 have reduced the specificity of reverse transcriptase-polymerase chain reaction, thereby reducing its clinical worth as a sensitive diagnostic technique.

We examined the expression of mRNA for cytokeratin 19 using a newly designed set of primers, and compared the results with data from histologic examinations. Samples were obtained from tumors, intact tissues, resected lymph nodes and in 10 patients who underwent esophagectomy via right thoracotomy with lymph node dissection in the neck, mediastinum and abdomen.

All tumors, non-cancerous tissues were positive for cytokeratin 19 by reverse transcriptasepolymerase chain reaction. However, 2 of the 6 lymph nodes that appeared normal on histologic examination were positive for cytokeratin 19; sensitivity and specificity were 100% and 67%, respectively.

Reverse transcriptase-polymerase chain reaction using new primers for cytokeratin 19 detected micrometastasis in specimens of lymph nodes from patients with squamous cell carcinoma. This method may increase the accuracy of tumor staging and provide clinicians with valuable information that will help individualize treatment options.