Differential Impact of Spread Through Air Spaces on Subtypes of Early-stage Lung Cancer.

Objective: To investigate the prognostic significance of STAS (Spread through air spaces) and its effect on survival in the various types of non-small cell lung cancer (NSCLC).

Study design: Descriptive analytical study. Place and Duration of the Study: Kartal Dr. Lutfi Kirdar City Hospital, Istanbul, Turkiye, between 2018 and 2021.

Methodology: Early-stage lung cancer patients who underwent lobectomy were included. STAS was defined as presence of tumour cell clumps, solid nests or set of single cells located in airway spaces apart from the main tumour border and determined by pathological work-up. The clinical significance of STAS was investigated by means of histopathological subtype, tumour size, and maximum standardised uptake value (SUVmax) on PET-CT scan in early-stage lung cancer by grouping it as adenocarcinoma and non-adenocarcinoma. Five-year overall and disease-free survival, and recurrence were the outcome measures.

Results: A total of 165 patients were included in the study. No recurrence was observed in 125 patients, 40 patients developed recurrence. Five-year overall survival (OS) was 69.6% in STAS (+) cohort and 74.5% in STAS (-) cohort (p=0.88). Five-year disease-free survival (DFS) was 51.1% in STAS (+) cohort and 73.1% for STAS (-) cohort (p=0.034). While the absence of STAS in the adenocarcinoma group was associated with better DFS, lower SUVMax and smaller tumour size, similar results were not found to be at statistically significant level in the non-adenocarcinoma group.

Conclusion: STAS positivity makes a difference in DFS, tumour size and SUVmax, especially in adenocarcinoma, however, it does not create a significant difference in survival or clinic pathological features in the non-adenocarcinoma.

Key words: Lung Cancer, Lobectomy, Spread through air spaces, Survival, Prognosis.