Prognostic Impact of Micrometastatic Tumor Cells in the Lymph Nodes and Bone Marrow of Patients With Completely Resected Stage I Non–Small-Cell Lung Cancer

Abstract

PURPOSE: This study was designed to substantiate the prognostic impact of occult micrometastatic tumor cells in the lymph nodes (LNs) and bone marrow (BM) in stage I non–small-cell lung cancer (NSCLC) patients using cytokeratin (CK) as a micrometastatic marker and the relationship between the micrometastases in the LNs and BM. PATIENTS AND METHODS: A total of 2,432 hilar and mediastinal LNs were removed during surgery from 115 patients with completely resected stage I NSCLC. The LNs were analyzed for micrometastasis using immunohistochemistry with the biclonal anti-CK antibody AE1/AE3. BM aspirates from 115 patients were immunocytochemically stained with the monoclonal anti-CK antibody CK2. RESULTS: CK-positive (CK+) cells were detected in 42 (1.7%) of 2,432 LNs, in 32 (27.8%) of 115 patients, and in 32 (27.8%) of 115 BM aspirates. There was no relationship between the frequencies of CK+ cells in the LNs and in the BM. The patients with CK+ cells in the LNs had a poor prognosis by both univariate (P = .008) and multivariate analyses (P = .01), whereas the presence of CK+ cells in the BM did not allow prediction of survival (P = .32). The prognostic impact of LNs micrometastasis was independent even after adjusting for the status of BM micrometastasis. CONCLUSION: The detection of lymph nodal micrometastatic tumor cells provides an accurate assessment of tumor staging and has powerful prognostic implications for completely resected stage I NSCLC patients.