Predictive Risk Factors for Mediastinal Lymph Node Metastasis in Clinical Stage IA Non-Small-Cell Lung Cancer Patients

Introduction: Even for patients with clinical N0 non-small-cell lung cancer (NSCLC), several invasive tests are available to pathologically confirm the presumptive mediastinal stage by radiologic modalities. The aim of this study was to determine a high-risk population for mediastinal nodal metastasis in patients with clinical stage IA NSCLC, which would be suitable for mediastinal staging by invasive modalities, such as mediastinoscopy or endobronchial ultrasound-guided transbronchial needle aspiration. Methods: We retrospectively reviewed peripheral clinical stage IA NSCLC patients who had undergone surgical resection with systematic mediastinal lymphadenectomy from 1998 to 2011. To identify predictors for mediastinal nodal metastasis, univariate and multivariate logistic regression analyses were performed. For the significant factors, optimal cutoff points were determined with a receiver operating characteristic analysis. Results: Among the 894 patients eligible for this study, the overall prevalence of mediastinal nodal metastasis was 7.5%. The following four predictors for mediastinal nodal metastasis were identified: age, preoperative serum carcinoembryonic antigen level, tumor size on preoperative radiologic findings, and consolidation/tumor ratio on high-resolution computed tomography. Of the patients with all four predictors identified by the multivariate analyses and receiver operating characteristic analyses (age <= 67 years, carcinoembryonic antigen >= 3.5 ng/ml, tumor size >= 2.0 cm, and consolidation/tumor ratio >= 89%), the prevalence of mediastinal nodal metastasis was 33.8%. Conclusions: Among the clinical stage IA NSCLC patients in whom all four predictors were identified, one third of the patients showed mediastinal nodal metastasis, and thus, those patients should be a target for mediastinal node assessment by invasive modalities, such as mediastinoscopy or endobronchial ultrasound-guided transbronchial needle aspiration.