Prognosis of spread through air spaces in invasive mucinous lung adenocarcinoma after curative surgery

Introduction The purpose of this study is to investigate the prognostic impact of spread through air spaces (STAS) in invasive mucinous adenocarcinoma (IMA). Materials and methods From 2015 to 2019, patients who underwent complete resection of IMA were extracted from the prospective database. Multivariable Cox-regression analysis and inverse probability of treatment weight (IPTW) - adjusted log-rank test for 5-year recurrence-free survival (RFS) were performed. Results STAS was observed in 39.1% (53 out of 133). The STAS (+) group shows larger tumor size (2.9 ± 2.4 cm vs 3.8 ± 2.4 cm, p = 0.031) and higher incidence of lympho-vascular invasion (6 7.5% vs 18 34.0%, p < 00.001) compared to the STAS (−) group. The 5-year RFS was 66.1% in the STAS (+) group and 91.8% in the STAS (−) group (p < 00.001), and the incidence of locoregional recurrence was significantly higher in the STAS (+) group than the STAS (−) group (1 1.2% vs 12 22.6%, p < 00.001). Multivariable analysis revealed that STAS was associated with poor prognosis for all-recurrence (hazard ratio 2.81, 95% confidence interval 1.01–7.81, p = 0.048). After IPTW adjustment, 5-year RFS was 66.3% in the STAS (+) group and 92.9% in the STAS (−) group (p = 0.007), and risk for locoregional recurrence was greater in the STAS (+) group than the STAS (−) group (1.1 0.9% vs 20.8 16.6%, p < 00.001). Conclusions STAS showed negative prognostic impact on all-recurrence, especially due to locoregional recurrence, after curative resection of IMA.