Immunohistochemical detection of micrometastases in regional lymph nodes of patients with stage I non-small cell lung cancer

Abstract

This study was designed to evaluate the incidence and clinical implications of immunohistochemical detection of micrometastases in the regional lymph nodes of patients with non-small cell lung cancer. The paraffin-embedded sections of 1, 024 regional lymph nodes from 56 patients with stage I non-small cell lung cancer who had undergone curative resection were studied. Immunohistochemistry with monoclonal antibody to cytokeratin 19 was used to detect micrometastases. We identified cytokeratin (CK)-positive cells in 15 (27%) of 56 patients, and in 22 (2.1%) of the 1, 024 lymph nodes. The frequency of micrometastases was more significantly in adenocarcinomas than in squamous cell carcinomas (p=0.041). Recurrence occurred more frequently in patients with micrometastases than without micrometastases (p=0.053). Survival was significantly shorter in the patients with micrometastases in the mediastinal lymph nodes than in patients with node-negative disease (p=0.037). These findings suggest that immunohistochemical staining for cytokeratin is useful for the detection of micrometastases to the regional lymph nodes, and can be a prognostic factor.