Significance of spread through air spaces in small cell lung cancer.

Purpose: Tumor spread through air space (STAS) is a novel pattern of invasion related to poor prognosis in non-small cell cancer (NSCLC). Nevertheless, little is known about the role of STAS in small cell lung cancer (SCLC). We sought to determine whether STAS has a significant effect on recurrence among SCLC patients.

Methods: We collected clinical and follow-up information from 181 resected stage I-III SCLC patients and compared overall survival (OS) and disease-free survival (DFS) between the patients with or without STAS using the Kaplan‒Meier method. To explore the effect of STAS on recurrence, a competing-risk analysis was conducted.

Results: Among 181 SCLC patients, STAS was observed in 56 (30.94%) patients, and 125 (69.06%) patients did not have STAS. Furthermore, 33 (18.23%) patients had recurrence, including 12 patients with brain metastases. Patients with STAS had worse DFS. The cumulative incidence of any recurrence was higher in patients with STAS than in those without STAS. Univariate and multivariate competing-risk regression analyses revealed that sublobar resection and STAS were independent risk factors for SCLC recurrence (p = 0.009 and p = 0.029 for multivariate analysis, respectively).

Conclusion: SCLC patients with STAS have worse DFS than SCLC patients without STAS. STAS is an independent prognostic factor in SCLC patients.