Prognostic impact of tumor spread through air spaces for T2aN0 stage IB non‐small cell lung cancer

BACKGROUND: Spread through air spaces (STAS) is a pattern of invasion recently identified in non‐small cell lung cancer (NSCLC), with a poor prognosis. However, the predictive impact of STAS in stage IB NSCLC is not well understood. This investigation aims to assess the prognostic influence of STAS in stage IB NSCLC. METHODS: We reviewed 130 resected stage IB NSCLC between 2010 and 2015. Beyond the central tumor edge, lung parenchymal air gaps containing cancer cells were identified as STAS. In order to estimate recurrence‐free survival (RFS) and overall survival (OS), Cox models and Kaplan–Meier techniques were utilized. Logistic regression analysis was employed to define the factors influencing STAS. RESULTS: Of 130 patients, 72 (55.4%) had STAS. STAS was a significant prognosticator. Kaplan–Meier method showed that STAS‐positive patients had a significantly lower OS and RFS than STAS‐negative patients (5‐year OS, 66.5% vs. 90.4%, p = 0.02; 5‐year RFS, 59.5% vs. 89.7%, p = 0.004) In a semiquantitative assessment, the RFS and OS were shorter in survival analysis when STAS increased (5‐year RFS, 89.7%, no STAS, 61.8%, low STAS, 57.2%, high STAS, p = 0.013; 5‐year OS, 90.4%, no STAS, 78.3%, low STAS, 57.2%, high STAS, p = 0.002). The association between STAS and poor differentiation, adenocarcinoma, and vascular invasion (p value was <0.001, 0.047, and 0.041, respectively) was statistically significant. CONCLUSIONS: The STAS is an aggressive pathological feature. RFS and OS could be significantly reduced by STAS, while it also serves as an independent predictor.