Clinical Characterization of Node-Negative Lung Adenocarcinoma: Results of a Prospective Investigation

Abstract

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. 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. 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. The serum CEA and HR-CT features thus allowed us to identify node-negative lung adenocarcinomas measuring 3 cm or less in size.