Sublobar Resection Is Associated with Decreased Overall Survival in Stage I Non-Small Cell Lung Cancer with Tumor Spread Through Air Spaces

B. Walker¹, J. R. Brady², J. C. Zajac³, D. McCarthy⁴, J. Maloney⁵, M. DeCamp¹, A. L.. Axtell^6
1University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin ²University of Wisconsin Clinics & Hospitals, Madison, Wisconsin ³University of Wisconsin Hospitals and Clinics, Madison, Wisconsin ⁴University of Wisconsin, Madison, Wisconsin ⁵UW Hospital and Clinics, Madison, Wisconsin ⁶University of Wisconsin, Verona, Wisconsin

Purpose: Patients with stage I lung cancer are increasingly being treated with sublobar resection. However, it is unknown whether patients with airspace invasion derive similar benefits. Therefore, we analyzed the association between tumor spread through air spaces (STAS) and overall survival, specifically in patients who underwent sublobar versus lobar resection.

Methods: A retrospective cohort analysis was conducted on 421 adult patients who underwent a first-time pulmonary resection for non-small cell lung cancer (NSCLC) at a single academic institution between January 2018 and December 2022. Patients prior to 2018 were excluded due to institutional non-reporting of STAS. Baseline clinical, operative, and pathologic characteristics were compared between patients who did and did not have STAS on final pathologic assessment. Overall survival and disease-free survival were compared between patients with and without STAS using the Kaplan-Meier and Cox proportional hazards regression models. Overall survival and disease-free survival were also compared in a predefined subgroup of stage I patients with and without STAS who underwent lobectomy versus sublobar resection (wedge resection or segmentectomy.)

Results: Of 421 patients who underwent a pulmonary resection for lung cancer, 97 (23%) had tumor STAS. There was no difference in STAS based on patient comorbidities or pulmonary function, however patients with STAS were more likely to have a higher pack year history of smoking (47 vs 40yrs, p=0.041). Histologically, patients with STAS were more likely to have adenocarcinoma (91% vs 78%, p=0.049) with micropapillary and papillary predominant features, a larger tumor size (2.6cm vs 2.2cm, p=0.016), concurrent lymphovascular invasion (46% vs 32%, p=0.012), and a more advanced pathologic stage (p=0.003). There was no difference in overall survival (p=0.993) or disease-free survival (p=0.157) for the entire cohort of patients with or without STAS. However, in the subgroup of patients with stage I disease, those who underwent sublobar resection and had STAS had significantly decreased overall survival compared to those without STAS (p=0.042) or those who underwent lobectomy, regardless of the presence or absence of STAS (Table 1.) Five-year overall survival was 73% for stage I patients with STAS who underwent sublobar resection compared to 87% in patients without STAS and 90% in patients without STAS who underwent lobectomy.

Conclusion: Tumor spread through air spaces is associated with pulmonary adenocarcinoma with papillary and micropapillary features. In patients with stage I disease, STAS is associated with decreased overall survival in patients who undergo sublobar resection; however STAS does not affect overall survival in patients who undergo lobectomy.

Identify the source of the funding for this research project: None