Detection of occult lymph node metastases in esophageal cancer by minimally invasive staging combined with molecular diagnostic techniques.
BACKGROUND AND OBJECTIVES: Lymph node metastases are the most important prognostic factor in patients with esophageal cancer. Histologic examination misses micrometastases in up to 20% of lymph nodes evaluated. In addition, non-invasive imaging modalities are not sensitive enough to detect small lymph nodes metastases. The objective of this study was to investigate the use of reverse transcriptase-polymerase chain reaction (RT-PCR) of messenger RNA (mRNA) for carcinoembryonic antigen (CEA) to increase the detection of micrometastases in lymph nodes from patients with esophageal cancer. METHODS: RT-PCR of CEA mRNA was performed in lymph nodes from patients with malignant and benign esophageal disease. Each specimen was examined histopathologically and by RT-PCR and the results were compared. RESULTS: Metastases were present in 29 of 60 (48%) lymph nodes sample by minimally invasive staging from 13 patients with esophageal cancer when examined histopathologically. RT-PCR identified nodal metastases in 46 of these 60 (77%) samples. RT-PCR detected CEA mRNA in all 29 histologically positive samples and in 17 histologically negative lymph nodes. All lymph nodes from patients with benign disease (n = 15) were negative both histopathologically and by RT-PCR. The stage of two patients was reclassified based on the RT-PCR results, which identified lymph node spread undetected histopathologically. Both of these patients developed recurrent disease after resection of the primary tumor. CONCLUSIONS: RT-PCR is more sensitive than histologic examination in the detection of lymph node metastases in esophageal cancer and can lead to diagnosis of a more advanced stage in some patients. The combination of minimally invasive surgical techniques in combination with new molecular diagnostic techniques may improve our ability to stage cancer patients.