Spread Through Air Spaces: Interresponder Agreement and Comparison Between Pulmonary and General Pathologists

Area of Science:

• Pulmonary Pathology
• Cancer Diagnosis
• Histopathology

Background:

• Spread Through Air Spaces (STAS) is a crucial prognostic indicator in lung cancer, defined by tumor clusters beyond the main mass.
• Accurate identification of STAS is vital for patient stratification and treatment planning.
• Current criteria for distinguishing STAS from artifacts lack universal consensus.

Purpose of the Study:

• To evaluate interobserver agreement on existing STAS diagnostic criteria versus artifacts.
• To identify specific areas of discrepancy in STAS interpretation.
• To compare diagnostic agreement between pulmonary and general pathologists.

Main Methods:

• An international online questionnaire assessed STAS vs. artifact interpretation.
• The study included members of professional pathology societies and course attendees.
• 136 responses were analyzed, with demographic and practice setting data collected.

Main Results:

• High agreement was observed for clearly defined STAS (≥3 alveolar spaces from tumor) and ciliated cell strips as artifacts.
• Lower agreement occurred with tumor clusters near the edge, single cells at the edge, jagged clusters, or mixed clusters with artifacts.
• No significant difference in agreement was found between pulmonary and general pathologists.

Conclusions:

• Significant interobserver agreement on STAS criteria is limited to a few specific scenarios.
• Areas with lower agreement require further clarification to enhance diagnostic reproducibility.
• Standardizing STAS interpretation is essential for its reliable use as a prognostic marker.