Comparison of three measurements on computed tomography for the prediction of less invasiveness in patients with clinical stage I non-small cell lung cancer.

BACKGROUND: A greater proportion of ground-glass opacity (GGO) is well known to be strongly associated with less invasive lung adenocarcinoma. Recently, the solid area diameter has also been reported to be a simple and better marker for the same purpose compared with the whole nodule diameter.
METHODS: From 1997 to 2009, 383 patients with clinical T1-2N0M0 non-small cell lung cancer (NSCLC) with a solid area of 3 cm or less underwent surgical resection, and their preoperative high-resolution computed tomographic images were preserved in Digital Imaging and Communications in Medicine format. Less invasive lung cancer was defined as having no vascular, lymphatic, or pleural invasion or lymph node metastasis. We compared the solid area and whole nodule diameters and proportion of GGO, with the objective of predicting less invasive lung cancer.
RESULTS: Among the 383 patients, 187 were men, 335 had adenocarcinoma histologic type, 242 had less invasive lung cancer, and 43 experienced recurrence. Receiver operating characteristic (ROC) analysis to predict less invasive lung cancer showed that the area under the curve of proportion of GGO was the highest (0.848; 95% confidence interval [CI], 0.810-0.886), followed by the solid area diameter (0.785; 95% CI, 0.740-0.829), and then whole nodule diameter (0.621; 95% CI, 0.565-0.677). Multiple logistic regression analyses revealed that proportion of GGO was the only significant predictor of less invasive lung cancer. The proportion of GGO was also found to be a significant prognostic factor of disease-free survival (DFS) along with solid area diameter by multivariate analysis. Regardless of the solid area diameter, no patient with a greater proportion of GGO (> 50%) experienced recurrence.
CONCLUSIONS: Proportion of GGO remains important for predicting less invasive lung cancer.