The prognostic impact of the ground-glass opacity component in nearly pure-solid stage IA non-small-cell lung cancer

The aim of this study was to assess the clinical effects of a small ground-glass opacity (GGO) component of a radiologically nearly pure-solid tumour on tumour aggressiveness in patients with clinical stage IA non-small-cell lung cancer (NSCLC). Data of 988 patients with clinical stage IA NSCLC who had a consolidation-to-tumour ratio of ≥0.75 on high-resolution computed tomography were retrospectively analysed. The cumulative incidence of recurrence (CIR) was compared between patients with GGO (nearly pure-solid, n = 297) and those without GGO (pure-solid, n = 691). In patients with clinical T1mi + T1a and T1b, the CIR was significantly higher in the pure-solid group than in the nearly pure-solid group (5-year CIR, 15.2% and 19.3% vs 0% and 6.4%; P < 0.001); however, this was not the case for patients with clinical T1c (5-year CIR, 23.1% vs 26.5%; P = 0.580). In the multivariable analysis, pure-solid tumours were independently associated with a higher CIR than nearly pure-solid tumours in patients with clinical T1mi + T1a + T1b (solid tumour size ≤2 cm; subdistribution hazard ratio, 3.25; 95% confidence interval, 1.59-6.63; P = 0.001) but not in those with clinical T1c tumours (2-3 cm; subdistribution hazard ratio, 0.67; 95% confidence interval, 0.39-1.13; P = 0.130). Nearly pure-solid tumours with a small GGO component influence tumour aggressiveness based on solid tumour size, with a threshold of 2 cm in patients with clinical stage IA NSCLC. For tumours sized 2-3 cm, nearly pure-solid tumours had a similar tumour aggressiveness as pure-solid tumours.