Prognostic Significance of Using Solid Versus Whole Tumor Size on High-resolution Computed Tomography for Predicting Pathologic Malignant Grade of Tumors in Clinical Stage IA Lung Adenocarcinoma: a Multicenter Study

Objectives: The present multicenter study compared the usefulness of the solid tumor size with that of the whole tumor size on preoperative high-resolution computed tomography for predicting pathologic high-grade malignancy (positive lymphatic, vascular, or pleural invasion) and the prognosis of clinical stage IA lung adenocarcinoma.

Methods: We performed high-resolution computed tomography and F-18 fluorodeoxyglucose-positron emission tomography/computed tomography before curative surgical resection in 502 patients with clinical stage IA lung adenocarcinoma. The revised maximum standardized uptake values on F-18 fluorodeoxyglucose-positron emission tomography/computed tomography were used to correct interinstitutional discrepancies. The whole and solid tumor sizes on high-resolution computed tomography were then analyzed in relation to surgical results.

Results: The mean whole and solid tumor size was 1.97 ± 0.59 cm and 1.20 ± 0.88 cm, respectively. The receiver operating characteristics area under the curve for the whole and solid tumor sizes used to identify high-grade malignancy were 0.590 and 0.829, respectively. Multiple logistic regression analyses demonstrated solid tumor size (P < .001) and maximum standardized uptake values of the tumor (P < .001) as independent variables for the prediction of high-grade malignancy. Multivariate Cox analysis of disease-free survival demonstrated the former (hazard ratio, 2.30; 95% confidence interval, 1.46-3.63; P < .001) and latter (hazard ratio, 1.08; 95% confidence interval, 1.00-1.17; P = .05) as independent prognostic factors.

Conclusions: The solid tumor size on high-resolution computed tomography and maximum standardized uptake values on positron emission tomography/computed tomography have greater predictive value for high-grade malignancy and prognosis in clinical stage IA lung adenocarcinoma than that of whole tumor size.