Diagnostic imaging, pathologic finding and prognostic correlation in patients with small peripheral carcinoma of the lung

We retrospectively studied the correlation between thin-section computed tomography (TS-CT) findings and both pathologic findings and prognosis in patients with small pulmonary adenocarcinomas (tumor diameter 20 mm or less). We then evaluated the usefulness of our classification by tumor shadow disappearance rate (TDR) on TS-CT findings for predicting outcome and formulating therapeutic strategy. A retrospective analysis was conducted including all 292 patients with small pulmonary adenocarcinomas between 1997 and 2005. Tumors were classified according to the percentage of TDR (cut-off value=30%, 40%, 50%) based on percentage of the length between images obtained lung-field and mediastinal setting on TS-CT images as the air type or the solid type. The air type (TDR cut-off value≥50%), revealed no microscopic involvement (pleural involvement, vascular invasion, or lymphatic invasion). The solid type (TDR cut-off value<50%) adenocarcinomas showed minimal microscopic involvement. Furthermore the disease-free survival curves of the air type revealed no relapses or cancer death, in contrast to the high relapse and death rate in the solid type. It seems likely that the TDR cut-off value of 50% may be treated successfully by limited lung resection in patients with small peripheral adenocarcinomas 20 mm or less in diameter on TS-CT. (author)