Molecular detection of occult nodal metastases in esophageal adenocarcinoma

Abstract

4540 Introduction: Esophageal adenocarcinoma (EAC) is an aggressive malignancy whose incidence is on the rise. Approximately 40% of patients with N0 disease will recur after theoretically curative surgery, suggesting that in early stage disease, metastatic spread is often undetected by routine pathology. Molecular techniques may more accurately detect micrometastatic spread of EAC, but the correlation between molecular analysis of nodes and prognosis is unknown. Our lab has previously identified and validated 4 markers whose gene expression levels are able to distinguish benign nodes from nodes with metastatic EAC: CK19, CK20, CEA and TACSTD1. We used quantitative real-time RT-PCR to evaluate the expression of these 4 markers in lymph nodes from 68 N0 and 62 N1 EAC patients to see if molecular staging is predictive of a worse clinical outcome. Methods: RNA was isolated from 1456 lymph nodes obtained from 130 patients who underwent resection of EAC. QRT-PCR was used to analyze gene expression for each of the 4 markers. Relative expression of each marker was compared with expression in 53 benign esophageal lymph nodes previously analyzed. Results: Analysis of 778 lymph nodes from 68 pN0 patients identified 71 nodes (9%) from 30 patients (44%) which showed positive expression of at least one marker, indicating occult metastases (and molecular upstaging). Analysis of 678 lymph nodes from 62 pN1 patients revealed 141 nodes (21%) from 40 patients (65%) which had positive expression of at least one marker in nodes that were pathologically negative. In the pathologically positive nodes from N1 patients, there was an encouraging 88% concordance between pathological and molecular analysis. After a median follow-up of 2 years, 13 N0 patients had recurrence of their cancer. Gene expression levels of 3 of the 4 markers (CK20, CEA and TACSTD1) correlated with significantly worse disease-free and overall survival among these N0 patients, with p values <0.05. Conclusion: We have shown that QRT-PCR of 3 independent genetic markers is predictive of significantly worse disease-free and overall survival among node-negative EAC patients by identifying lymph nodes with occult metastatic disease. Further analysis will reveal if the N1 patients with molecularly positive lymph nodes had significantly worse outcomes as well. No significant financial relationships to disclose.