The impact of STAS on recurrence-free and overall survival in T1-2N0 adenocarcinomas: a single-center retrospective study

Background Adenocarcinoma (AC) is the leading histopathological type of lung cancer (LC), curative surgery being the cornerstone for the best survival results. However, even in the patients who had curative surgery, the survival outcomes differ. Spread through air spaces (STAS), recognized as a histopathological feature in the 2015 World Health Organization (WHO) Classification, causes poor survival outcomes in lung AC. This study aimed to evaluate the prognostic impact of STAS on recurrence-free survival (RFS) and overall survival (OS) in surgically resected T1-2N0 lung AC, with particular attention to its interaction with tumor size. Methods This single center retrospective study evaluates the effect of STAS on RFS and OS in 296 surgically resected T1-2N0 lung AC patients. For further analysis, patients were divided into four subgroups combining their STAS status and tumor size. Results STAS presence rate was 37.5%, which was associated with aggressive tumor characteristics, such as non-lepidic predominant subtypes, higher pathological T stage (pT), visceral pleura invasion (VPI), and lymphovascular invasion (LVI). OS and RFS were significantly worse in the STAS-Present (STAS-P) group ( p = 0.030). Subgroup analysis revealed that STAS-P tumors > 2 cm had the worst outcomes, as expected. Notably, on univariate analysis STAS presence appeared most prognostically decisive in tumors ≤ 2 cm, in which there was no significant difference in survival between STAS-P tumors ≤ 2 cm and STAS-Absent (STAS-A) tumors > 2 cm. Conclusions STAS was a significant prognostic factor on univariate analysis but did not retain independent significance after multivariable adjustment. In an exploratory subgroup analysis, STAS-P tumors ≤ 2 cm carried survival outcomes comparable to STAS-A tumors > 2 cm, suggesting STAS may attenuate the prognostic advantage of smaller tumor size. This hypothesis-generating finding warrants prospective validation before informing surgical management.