The spread through air spaces (STAS) has a main role in local recurrence of stage I lung adenocarcinomas (LAs), therefore its presence might question sublobar resection as a therapeutic option. The aim of our study was to evaluate the distribution of STAS in stage I LAs, to stratify patients according to local recurrence and to identify a group of patients who might be suitable for sublobar surgery. Patients resected with LA were included. The presence of STAS was recorded on hematoxylin eosin stained slides and clinicopathological data were obtained from medical charts. Overall survival (OS) and disease-free survival (DFS) were registered. Statistical methods included Kruskal-Wallis tests, Kaplan-Meier analyses, log-rank tests and Cox-regressions. 292 patients were included. STAS was identified in 38.7% and 95.7% of micropapillary carcinomas showed STAS. Significant correlation was found between STAS and high-grade patterns. Significant differences were found between OS and DFS estimates of STAS0 and STAS1 cases (5-y-OS: 80.0% vs. 68.4%; 5-y-DFS: 71.1% vs. 57.1%). The presence of STAS was associated with unfavorable prognosis in low and intermediate architectural grades, but not in high-grade. Multivariate analysis revealed that architectural grade (HR(OS):2.09; HR(DFS):1.52) and STAS (HR(OS):1.51; HR(DFS):1.48) were independent prognostic markers in stage I LA. Architectural grade combined with STAS was superior to other prognostic grades. The combination of architectural grade and STAS proved to be a prognostic factor that is superior to previously introduced grading systems. Patients having low and intermediate grade LAs without STAS might be eligible for sublobar resection.
Keywords: Architectural grade; Lung adenocarcinoma; Lung sparing surgery; Spread through airspaces (STAS); Sublobar resection.