on Cancer; MIA, minimally invasive adenocarcinoma; RFS, recurrence-free survival; CIR, cumulative incidence of recurrence; OS, overall survival; DFS, disease-free survival; CEA, carcinoembryonic antigen; SUV, standardized uptake value; PET, positron emission tomography; CT, computed tomography.
2758Morales-Oyarvide and Mino-Kenudson. Towards a quantitative approach to tumor spread through air spaces (STAS)© Journal of Thoracic Disease. All rights reserved. J Thorac Dis 2017;9(9):2756-2761 jtd.amegroups.com had high STAS. Higher amounts of STAS were associated with pleural invasion (P<0.001), lymphovascular invasion (P<0.001), and tumor size ≥10 mm (P=0.037). The quantity of STAS was also associated with predominant histologic pattern. While solid-predominant pattern was found in 16% of tumors with high STAS, it was seen only in 8% and 2% of those with low and no STAS, respectively (P<0.001). Conversely, lepidic-predominant pattern was observed in only 3% of tumors with high STAS, and in 16% of both low and no STAS tumors (P<0.001). Notably, the authors did not report on the relationship between STAS and the micropapillary-predominant histologic pattern.Importantly, high amounts of STAS were associated with higher risk of recurrence and mortality compared to no STAS. After adjusting for presence of lymphovascular invasion and the predominant histologic pattern, patients with high STAS had a hazard ratio (HR) for RFS of 7.34 (95% CI: 1.54-35.17) compared to patients with no STAS, and this difference was statistically significant. When compared to patients with low STAS, those with high STAS had higher risk of recurrence but this had limited statistical significance (HR for RFS 4.45, Interestingly, nearly all patients with high STAS underwent lobectomy (95%), compared with 79% and 69% of patients with low and no STAS, respectively (P<0.001). Thus, the authors performed secondary analyses stratified by the type of resection. In patients who underwent lobectomy, high STAS was associated with worse RFS (median 140.4, 150.4, and 116.3 months for patients with no-, low-, and high STAS, respectively, P<0.001). Among patients who underwent limited resection, there was a strong trend towards worse RFS in those with high STAS (median 152.9, 117.5, and 85.8 months for patients with no-, low-, and high STAS, respectively, P=0.084) but it did not reach statistical significance, possibly due to the small number of patients in the limited resection group (n=45).In summary, the study by Uruga et al. confirms the previous findings that presence of STAS is associated with adverse pathological features such as lymphovascular invasion and solid-predominant histologic pattern of invasion. The novel and most important finding of this study is the prognostic relevance of the amount of STAS in a tumor, beyond its mere presence or absence. The results clearly demonstrated that high amounts of STAS (defined as 5 or more clusters/single tumor cells) were associated with poor RFS and OS compared to no STAS. Whether high amounts of STAS are a...