Radiological classification of multiple lung cancers and the prognostic impact based on the presence of a ground glass opacity component on thin-section computed tomography

•The prognosis of multiple lung cancers differs based on the radiological characteristics.•A simple presence of a GGO component would be a favorable prognosticator in multiple lung cancers.•The PS + PS group would be considered as a strong candidate for upgrading of clinical T descriptors.

ObjectivesRevised TNM classification has proposed a new clinical classification of lung cancers with multiple pulmonary sites. However, definition of the radiological findings and their prognostic impacts are still controversial. Therefore, we evaluated the prognostic impact of multiple lung cancers based on the radiologic classifications concluded from findings on thin-section computed tomography.MethodsAmong surgically resected 1440 c-stage I lung cancer patients, 246 (17.1%) with multiple lung tumors were reviewed. All tumors were classified into 3 groups based on the extent of ground glass opacity (GGO), i.e., consolidation tumor ratio (CTR); GGO-dominant (GD; 0 ≤ CTR < 0.5), solid-dominant (SD; 0.5 ≤ CTR < 1.0) and pure-solid (PS; CTR = 1.0). Multiple lung tumors were divided radiologically into 6 groups, and their prognoses were compared with that of c-stage I lung cancer using Cox's proportional hazard model.ResultsOf all, 198 patients (80.5%) were surgically resected more than two tumors and determined as multiple lung cancers pathologically. The number of patients with GD + GD = 73 (30%), GD + SD = 54 (22%), GD + PS = 53 (21%), SD + SD = 12 (5%), SD + PS = 20 (8%) and PS + PS = 34 (14%). A multivariate analysis revealed that PS + PS group consisted of independently significant prognosticator (p < 0.001). The overall survival (OS) was 97.3% in GD + GD, 98.2% in GD + SD, 84.8% in GD + PS, 90.9% in SD + SD, 78.7% in SD + PS and 41.8% in PS + PS groups, showing a significant difference between PS + PS group and the other groups. Furthermore, the OS of 1194 c-stage I lung cancer patients was 78.2%, and the prognosis of PS + PS group was significantly poor compared with that of c-stage I (p < 0.001), while OS of the other groups were almost equivalent or much better than the c-stage I.ConclusionsAmong multiple lung cancers, PS + PS group is associated with poor survival, which would contribute to the upstaging of T descriptors. The presence of GGO is extremely important when considering the correlation between radiological classification of multiple lung cancers and its prognosis.