Measurement of Multiple Solid Portions in Part-Solid Nodules for T Categorization: Evaluation of Prognostic Implication

Introduction: Our study aimed to analyze the prognostic implication of the multiplicity of solid portions in part-solid nodules (PSNs) on computed tomography scans and compare the prognostic performance of various measures of solid portions, including the single largest solid portion, solid proportion, and summated multiple solid portion measurements. Methods: The cases of a total of 345 patients with surgically resected stage IA adenocarcinomas manifesting as PSNs were retrospectively reviewed. The multiplicity of the solid portion in PSNs was determined and the diameter of each solid portion was measured. The prognostic implication of the multiplicity of the solid portion and other clinical variables in relation to disease-free survival (DFS) was analyzed by using Cox regression. In addition, risk stratification based on the single largest solid portion, sum of the solid portions, single solid proportion, and sum of the solid proportions was conducted. Next, concordance indices (C-indices) for DFS were obtained for each measure and compared. Intrareader and interreader measurement variability was assessed. Results: Multiplicity of the solid portion did not have a significant effect on DFS; clinical T category was the only independent risk factor for tumor recurrence (p < 0.05). The C-index of the single solid portion (conventional clinical T category) was 0.817 (95% confidence interval: 0.691-0.942). There were no significant differences (p > 0.05) between the C-indices of the single solid portion and other solid portion measures. Interreader measurement variability was substantial. Conclusions: The current clinical T categorization of PSNs based on the single solid portion measurement is appropriate. (C) 2018 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.