The prognosis of patients with cT1N0 lung adenocarcinoma is better when tumors include mixed ground glass opacity (GGO), compared with pure solid tumors. However, whether the prognosis of patients with mixed GGO tumors is favorable regardless of the solid component size remains unknown. Therefore, we aimed to determine the prognostic role of the solid component size in mixed GGO.
We retrospectively analyzed the clinicopathological findings and prognoses of 856 patients with mixed GGO tumors based on solid component size during a median follow-up of 45 months, among 1215 patients with cT1N0 lung adenocarcinoma according to the TNM Classification of Malignant Tumors, Eighth Edition, who underwent R0 resection at 3 institutions between 2010 and 2015.
Four-year recurrence-free survival rates were significantly worse for patients with mixed GGO cT1c tumors (solid component size: 2-3 cm; 81.5%; 95% confidence interval [CI], 72.8%-87.7%) than for those with cT1mi+1a tumors (0-1 cm; 96.8%; 95% CI, 94.2%-98.2%) and cT1b (1-2 cm; 95.3%; 95% CI, 92.1%-97.2%) (both P < .001), although that for cT1b tumors was comparably favorable to those of T1mi+1a tumors. Multivariable Cox regression analysis of recurrence-free survival revealed that a solid component size of 2 cm to 3 cm (cT1c) vs less than or equal to 2 cm (cT1mi+1a+1b) was an independent prognostic factor (hazard ratio, 4.16; 95% CI, 2.24-7.72; P < .001).
The prognostic impact of a solid component size less than or equal to 2 cm and greater than 2 cm significantly differs after complete resection of GGO-mixed T1N0 lung adenocarcinoma. The prognosis of patients with solid components less than or equal to 2 cm is favorable, whereas the behavior of those solid components greater than 2 cm is more aggressive.