Prognostic Impact of Tumor Spread Through Air Spaces in Non-small Cell Lung Cancers: a Meta-Analysis Including 3564 Patients.

Surgical resection is the most effective treatment for early stage lung adenocarcinoma. However, the rate of 5-year postoperative recurrence reaches 30%, Spread Through Air Spaces(STAS) is a recently described novel invasive pattern of lung cancer, According to the 2015 WHO classification. STAS is defined as"micropapillary clusters, solid nests, or single cells spreading within air spaces beyond the edge of the main tumor, However, the prognostic role of STAS in lung cancer is not known, The aim of the current study is to evaluate the association between STAS and clinical outcome of lung cancer patients after surgical resection through a meta-analysis. Systematic research was conducted using three online databases to search for studies published before August 1, 2018. The 5-year RFS and OS for non-small cell lung cancer patients after surgical resection with or without STAS were compared. The studies were selected according to rigorous inclusion and exclusion criteria. Meta-analysis was performed using hazard ratio (HR) and 95% confidence intervals (CIs) as effective measures. Included in our meta-analysis were 12 studies, published from 2015 to 2018, with a total of 3564 patients. Our results clearly depicted that the presence of STAS predicted a worse outcome for 5-year RFS with the combined HR of 1.84(95% CI: 1.59-2.12). Meta-analysis of these 8 studies showed that patients with the presence of STAS were associated with shorter 5-year OS (the pooled HR:1.78, 95% CI: 1.51-2.11). This meta-analysis illuminated that the presence of STAS might be a unfavorable prognostic factor for patients with NSCLC. it should be paid sufficient attention and recorded in pathologic reports, which can indicate treatment choice and prognosis of patients. In future, more studies with well-designed and large-scale are needed to confirm the conclusion.