Prognostic Impact of Margin Distance and Tumor Spread Through Air Spaces in Limited Resection for Primary Lung Cancer

Objectives The aim of this study was to investigate the relationship between clinicopathological prognostic factors, including surgical margin distance and tumor spread through air spaces (STAS), and recurrence after limited resection for primary lung cancer. Methods We identified 508 cases of limited resection (12.8%) and examined their clinicopathological features. Using Cox regression analysis, we examined the significant prognostic factors for recurrence of limited resection. Finally, we conducted a histopathological evaluation of tumor STAS. Results Multivariate Cox analysis showed that the risk for local recurrence was significantly associated with STAS (hazard ratio = 12.24, p = 0.001) and a tumor margin less than 1.0 cm (hazard ratio = 6.36, p = 0.02). However, the presence of tumor STAS was not significantly associated with distant recurrence (p = 0.98). This lack of association of STAS with distant recurrence may be due to the small number of distant recurrences. In all, 76 cases (15.0%) (60 adenocarcinomas, nine squamous cell carcinomas, and seven others) were positive for STAS. The morphological STAS patterns were 12 single cells, 45 small cell clusters, and 19 large nests. There was no significant relationship between the recurrence rate and morphological STAS pattern. The STAS-positive group was associated with the presence of micropapillary (p = 0.002) and/or solid components (p = 0.008) in patients with adenocarcinoma and with lymphovascular and pleural invasion (p < 0.001). Conclusions The presence of STAS and tumor margins less than 1.0 cm are significant risk factors for local recurrence in early-stage lung cancer after limited resection. Thus, the presence of tumor STAS might be a pathological prognostic factor for patients with lung cancer who have undergone limited resection. However, the pathological and molecular significance of STAS remain to be clarified.