P3.01-002 The Clinical Impact of Spread through Air Spaces (STAS) in Surgically Resected pStage I Lung Squamous Cell Carcinoma: Topic: Morphology

Abstract

Spread through air spaces (STAS) is identified as a newly invasive pattern in lung adenocarcinoma. It contributes to the significantly increased recurrence rate for patients with small adenocarcinoma. But the presence of STAS and its clinical impact has remained uncertain in squamous cell carcinoma (SQCC). The purpose of this study is to analyze whether STAS happens in surgically resected pathological Stage I (pStage I) lung SQCC. We retrospectively reviewed 141 pStage I patients of SQCC (Female/Male, 13/128; Smoker/Never smoker, 135/6; pStage IA/IB, 93/48). Tumor STAS was defined as tumor cells within the air spaces in the lung parenchyma beyond the edge of the main tumor. Statistical analyses were conducted to investigate the relationship between its presence and the clinicopathological background factors, including the clinical outcome. STAS was identified in 23 of 141 patients (16.3%) with limited (7.1%) and extensive (9.2%) feature, respectively. Both disease-free survival (DFS) and overall survival (OS) were significantly worse in the patients with STAS in comparison with the patients without STAS (5-year DFS, 35.1% vs. 65.6%, p<0.01; 5-year OS, 41.7% vs. 71.2%, p<0.01, respectively). In multivariate analyses adjusting for sex, year, smoking history and pStage, the presence of STAS was found to be an independent predictive factor of both DFS (HR=3.154, 95%CI: 1.592-6.249; p=0.001) and OS (HR=3.07, 95%CI: 1.595-5.911; p=0.0008). The 141 tumors were divided into patients who underwent limited resection and those who underwent standard resection in order to examine whether the surgical procedure affected the DFS and OS of patients with and without STAS. In the standard resection group, both 5-year DFS and 5-year OS were worse in the patients with STAS in comparison with the patients without STAS (44.1% vs. 68.3%, p=0.03; 53.8% vs. 72.3%, p=0.048, respectively). In the limited resection group, both 5-year DFS and 5-year OS were worse in the patients with STAS in comparison with the patients without STAS (0% vs.57.5%, p=0.001; 0% vs. 66.4%, p=0.001, respectively). STAS happened in lung SQCC and was found to be an independent predictive factor of both DFS and OS. Both 5-year DFS and 5-year OS were worse in the patients with STAS regardless of surgical procedure.