Spread Through Airspaces (STAS) Associated with Poor Prognosis in Early-Stage NSCLC Across Lobectomy and Segmentectomy Procedures

Barcelona, Spain (September 8, 2025 10:45 a.m.) — The presence of spread through airspaces (STAS) is an independent predictor of worse survival outcomes in early-stage non-small cell lung cancer (NSCLC), regardless of surgical approach, according to new research presented at the International Association for the Study of Lung Cancer (IASLC) 2025 World Conference on Lung Cancer (WCLC).

STAS occurs when tumor cells are found floating within the air spaces of the lung (the alveoli) beyond the main edge of the tumor. These cancer cells are detached from the primary tumor mass and are present in the surrounding lung tissue air spaces where they can grow into new tumors. STAS is not detectable by CT scan and must be identified under microscope.

The Phase III JCOG0802/WJOG4607L trial compared segmentectomy versus lobectomy for T1aN0 (≤ 2.0 cm) NSCLC in a randomized, multicenter, non-inferiority study. In this analysis, 32 IASLC Pathology Committee pathologists from 15 countries reviewed 646 digitized histology slides (one per case) for multiple histologic features, including STAS and IASLC histologic grade. Six cases were excluded, resulting in 640 evaluable cases.

Key findings presented by Yasushi Yatabe, MD, PhD, of the National Cancer Center, Japan, include:

• STAS was detected in 35.5% of cases, consistent with previous studies and was associated with significantly shorter relapse-free survival (RFS; HR=2.050, 95% CI 1.462–2.874) and overall survival (OS; HR=2.340, 95% CI 1.704–3.212), both p<0.001.
• In multivariable analysis, STAS remained an independent poor prognostic factor for both RFS (p<0.001) and OS (p=0.004).
• Across both lobectomy and segmentectomy subgroups, STAS-positive tumors had higher local recurrence rates (p<0.01) and worse RFS; OS was significantly impacted only in the lobectomy subgroup (p=0.019).
• Among 487 patients with invasive non-mucinous adenocarcinoma, histologic grade 3 was strongly associated with STAS (p<0.001) and poor outcomes. Both STAS and grade 3 independently predicted shorter RFS.

“Our study confirms that STAS is a powerful prognostic marker in early-stage NSCLC and should be considered when planning surgical and follow-up strategies,” said Dr. Yatabe. “The findings emphasize the importance of integrating detailed pathological review into treatment decision-making.”

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About the IASLC:
The International Association for the Study of Lung Cancer (IASLC) is the only global organization dedicated solely to the study of lung cancer and other thoracic malignancies. Founded in 1974, the association's membership includes more than 10,000 lung cancer specialists across all disciplines in over 100 countries, forming a global network working together to conquer lung and thoracic cancers worldwide. The association also publishes the Journal of Thoracic Oncology, the primary educational and informational publication for topics relevant to the prevention, detection, diagnosis, and treatment of all thoracic malignancies. Visit www.iaslc.org for more information.

About the WCLC:
The WCLC is the world’s largest meeting dedicated to lung cancer and other thoracic malignancies, attracting nearly 7,000 researchers, physicians, and specialists from more than 100 countries. The goal is to increase awareness, collaboration and understanding of lung cancer, and to help participants implement the latest developments across the globe. The conference will cover a wide range of disciplines and unveil several research studies and clinical trial results. For more information, visit https://wclc.iaslc.org/.