Background: STAS(Spread Through Air Spaces) was first described as a ?collection of tumor cells within an alveolar space? that are related to each other and the main tumor. Several studies have demonstrated STAS as an independent prognostic factor in patients with pulmonary adenocarcinoma.

Objective: We ought to compare clinicopathological and molecular characteristics between subjects with and without STAS, as well as Disease-Free Survival(DFS).

Methods: We assessed retrospectively 57 patients who were diagnose with stageI-III resected pulmonary adenocarcinoma. Fisher exact test and Mann-Whitney U test were used to evaluate the association between STAS and clinicopathologic characteristics. DFS was estimated using Kaplan-Meier method.

Results:21(36,8%) subjects were female and median age at diagnosis was 65(62-67). Median follow up time was 3,5 years(2,9-4,0). Lobectomy was performed in 47(82,5%) subjects. Most subjects presented with stage I at diagnosis. STAS was present in 19(33,3%) cases. Subjects with STAS were significantly more likely to have a micropapillary pattern present in the histology(58,8% vs 25%, p = 0,019), and to be associated with lymphatic(47,4% vs 13,2%, p = 0,008) and pleural(68,4% vs 36,8%, p = 0,047) invasion. No association was found between the group with STAS and the group without STAS regarding sex, age, smoking history, pathologic stage, predominant histologic patterns, and molecular biomarkers. Median DFS in patients with and without STAS was 10,7 months(9,9-11,5) and 16,9 months(0,0-46,8), respectively, showing trends of worse DFS in patients with STAS(log rank p=0,072).

Conclusion:STAS comprises a clinicopathologic aggressive feature and may be associated with worse DFS in adenocarcinoma.