Is limited resection appropriate for radiologically "solid" tumors in small lung cancers?

Small lung cancers showing a wide area of ground-grass opacity (GGO) on thin-section computed tomography (CT) are considered good candidates for limited surgical resection because of its minimally invasive nature. Conversely, the validity of limited resection for radiologically "solid" tumors is still controversial in small non-small cell lung carcinomas.

Between 2008 and 2010, 680 consecutive patients underwent pulmonary resection for lung cancer. The findings obtained by preoperative CT were reviewed for all 680 patients and categorized as pure GGO, mixed GGO, or purely solid. All patients were evaluated by positron emission tomography (PET) and the maximum standardized uptake value (SUV(max)) was recorded. Several clinicopathologic features were investigated to identify predictors of hilar or mediastinal lymph node metastasis using univariate or multivariate analysis.

Two hundred twenty-seven of the patients with clinical stage IA lung cancer showed a solid or mixed GGO appearance on thin-section CT. Among them, nodal involvement was found pathologically in 42 (26%) patients with pure solid tumors, but in only 4 (6%) patients with mixed GGO tumors (p = 0.0002). Among the 131 patients with stage T1a disease, 94 (71.8%) had solid tumors, and nodal involvement was observed in 15 (16.0%). Among the 94 pure solid stage T1a tumors, the carcinoembryonic antigen (CEA) level and SUV(max) were significant predictors of lymph node involvement by tumor based on a multivariate analysis. The frequency of lymph node metastasis was approximately 27% for patients with pure "solid" lung cancer and high SUV(max), even for stage T1a tumor.

Lymph node metastasis is frequently observed for pure solid lung cancer, especially for tumors that show a high SUV(max). If limited resection is indicated for solid lung cancer, a thorough intraoperative evaluation of lymph nodes is needed to prevent locoregional failure.