Clinical characterization of node-negative lung adenocarcinoma: Results of a prospective investigation

OBJECTIVES: In clinical stage IA lung adenocarcinoma, the clinical features of a truly node-negative population were prospectively investigated by means of a prospective investigational study. METHODS: The clinical data and radiographic features of high-resolution computed tomography (HR-CT) were registered before operation in 169 clinical stage IA lung cancer patients who were scheduled to undergo a standard lobectomy and systemic mediastinal node dissection. The nodal metastasis was pathologically defined and the clinical factors associated with the presence of the nodal metastasis were evaluated. RESULTS: In 114 assessable cases with adenocarcinomas, 15 (13.1%) were node-positive. The serum carcinoembryonic antigen (CEA), retraction sign, and intratumoral air-bronchogram on HR-CT were suggested to be predictive factors for lymph node metastasis, with hazard ratios of 12.44 (p = 0.0003), 6.53 (p = 0.0533), and 0.17 (p = 0.0073), respectively. In combination with the radiologic features and serum CEA, cases with elevated serum CEA or presence of retraction sign included 15.6% of node metastasis-positive, whereas all cases with normal CEA and absence of retraction sign showed no nodal metastasis. Cases with elevated serum CEA or absence of intratumoral air-bronchogram included 24.5% of node metastasis, whereas cases with normal CEA and presence of air-bronchogram showed 4.6% of node metastasis. The tumor size and the proportion of ground-glass attenuation were not associated with the incidence of nodal metastasis. CONCLUSIONS: The serum CEA and HR-CT features thus allowed us to identify node-negative lung adenocarcinomas measuring 3 cm or less in size.