title: Semiquantitative Assessment of Tumor Spread through Air Spaces (STAS) in Early-Stage Lung Adenocarcinomas.
abstract: Tumor spread through air spaces (STAS) has recently been reported as a form of tumor invasion having an unfavorable prognosis, but the significance of a small amount of STAS is not known. The aim of this study was to perform a semiquantitative assessment of STAS.
  
  
  
  Small (≤2 cm) stage I lung adenocarcinomas surgically resected at our institution between 2003 and 2009 were assessed semiquantitatively in the most prominent area as no STAS, low STAS (1-4 single cells or clusters of STAS), or high STAS (≥5 single cells or clusters of STAS) by using a 20× objective and a 10× ocular lens. A statistical analysis was performed to determine the impact of clinicopathologic parameters on STAS and to clarify the relationship between STAS and patient survival.
  
  
  
  STAS was assessed as no STAS in 109 of 208 cases (52.4%), as low STAS in 38 cases (18.3%), and as high STAS in 61 cases (29.3%). There were statistically significant associations between higher STAS and solid predominant invasive adenocarcinoma (p < 0.001), pleural invasion (p < 0.001), lymphatic invasion (p < 0.001), vascular invasion (p < 0.001), and tumor size of 10 mm or more (p = 0.037). There was a significant association between increasing STAS and shorter recurrence-free survival (RFS) in univariate analysis (no STAS, 154.2 months; low STAS, 147.6 months; and high STAS, 115.6 months). In a multivariate Cox proportional hazards model, only STAS (p = 0.015) remained a significant predictor of RFS.
  
  
  
  We found that one-third of resected small adenocarcinomas had high STAS. Higher STAS was predictive of worse RFS.
authors.affiliation: Department of Respiratory Medicine, Respiratory Center, Toranomon Hospital, Tokyo, Japan; Department of Diagnostic Pathology, Toranomon Hospital, Tokyo, Japan; Okinaka Memorial Institute for Medical Research, Tokyo, Japan. Electronic address: uruga.hironori@gmail.com.
authors.forename: Hironori
authors.initials: H
authors.lastname: Uruga
authors.affiliation: Department of Diagnostic Pathology, Toranomon Hospital, Tokyo, Japan; Okinaka Memorial Institute for Medical Research, Tokyo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fujii
authors.affiliation: Department of Thoracic Surgery, Respiratory Center, Toranomon Hospital, Tokyo, Japan.
authors.forename: Sakashi
authors.initials: S
authors.lastname: Fujimori
authors.affiliation: Department of Thoracic Surgery, Respiratory Center, Toranomon Hospital, Tokyo, Japan.
authors.forename: Tadasu
authors.initials: T
authors.lastname: Kohno
authors.affiliation: Department of Respiratory Medicine, Respiratory Center, Toranomon Hospital, Tokyo, Japan; Okinaka Memorial Institute for Medical Research, Tokyo, Japan.
authors.forename: Kazuma
authors.initials: K
authors.lastname: Kishi
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D000077192:Adenocarcinoma of Lung; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D011379:Prognosis
keywords: Invasion; Lung adenocarcinoma; Recurrence; Tumor spread through air spaces