# Spread through air spaces (STAS)

Source: https://onco.cc/terms/spread-through-air-spaces/  
OnCo record `spread-through-air-spaces` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Clusters of tumour cells found floating in the air sacs beyond the edge of the main tumour. The 2021 WHO classification recognised it as a real prognostic feature rather than an artefact of cutting the specimen, and it argues against taking out only part of a lobe.

## Summary

Spread through air spaces is the presence of tumour cells, as micropapillary clusters, solid nests or single cells, within the alveolar spaces of the lung beyond the edge of the main tumour. It was contested for years as a possible artefact of the knife dragging cells across the specimen, and the fifth edition of the WHO classification of thoracic tumours settled the argument by recognising it as a histological feature with prognostic significance (Nicholson 2022). It matters most for the operation: a tumour that has spread through air spaces has cells beyond its visible margin, which is the argument for taking the whole lobe rather than a wedge or segment in a tumour that might otherwise have had a sublobar resection. It is reported on resection specimens; it cannot be assessed on a needle biopsy, so it is a finding that arrives after the decision it bears on. It sits alongside the other changes the 2021 edition made to how lung adenocarcinoma is reported: grading by the percentage of each growth pattern, and measuring only the invasive component for the T size in part-lepidic tumours.

## Fields

- Kind: Term
- Last checked: 2026-09-25
- Also known as: STAS; spread through air spaces; tumour spread through air spaces; airspace spread
- Tags: lung

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Adenocarcinoma_of_the_lung
- Nicholson, J Thorac Oncol 2022: the 2021 WHO classification of lung tumours, impact of advances since 2015: https://doi.org/10.1016/j.jtho.2021.11.003

## Connected records

- cancers: [Adenocarcinoma in situ and minimally invasive adenocarcinoma of the lung](https://onco.cc/cancers/lung-adenocarcinoma-in-situ-and-minimally-invasive/), [Adenocarcinoma of the lung](https://onco.cc/cancers/lung-adenocarcinoma/), [Lung cancer (all types)](https://onco.cc/cancers/lung-cancer/), [Non-small-cell lung cancer](https://onco.cc/cancers/nsclc/)
- technologies: [Histopathology & immunohistochemistry](https://onco.cc/technologies/histopathology-ihc/)
- terms: [Pulmonary nodule](https://onco.cc/terms/pulmonary-nodule/), [Resectability in lung cancer](https://onco.cc/terms/resectability-lung-cancer/), [Sublobar resection (segmentectomy and wedge)](https://onco.cc/terms/sublobar-resection/), [TNM 9: what changed in lung cancer staging](https://onco.cc/terms/tnm-9-lung-cancer/), [TTF-1 and p40 (how lung histology is decided)](https://onco.cc/terms/ttf1-p40/)

---
JSON: https://onco.cc/api/v1/entities/spread-through-air-spaces.json