Measure the primary and name what it touches (T), map nodes by IASLC station (N), and look for metastases in the adrenals, liver, bone and brain (M) — using the TNM edition your centre reports in.
Orient first
- T is decided by size AND by invasion: chest wall, mediastinal structures, the diaphragm and separate nodules in the same or another lobe all change the T category regardless of size.
- N is by station, not by size alone: hilar/intrapulmonary (N1), ipsilateral mediastinal or subcarinal (N2), contralateral or supraclavicular (N3).
- The TNM edition changes category boundaries — the 9th edition split some N2 and M1c categories; state the edition and verify the thresholds you quote against it.
Acquire the study
- Contrast-enhanced CT chest to the adrenals in the portal venous phase; lung and mediastinal windows; multiplanar reformats.
The manoeuvre
- Primary: longest diameter of the solid component on lung window (for part-solid tumours measure the solid part).
- Invasion on mediastinal window and reformats: chest wall and ribs, mediastinal fat, pericardium, great vessels, carina, diaphragm, phrenic or recurrent laryngeal nerve territory.
- Additional nodules: same lobe (T3), different ipsilateral lobe (T4), contralateral lung (M1a) — measure each.
- Nodes by IASLC station with short-axis size; a short axis over 10 mm raises suspicion but a normal-size node can be involved.
- Pleural or pericardial effusion or nodules (M1a); adrenals, liver and bone on the included sections.
What confirms it
- A complete TNM stage with the edition named and the features that set each category.
What licenses you to exclude it
- A normal PET-CT for nodes lowers but does not remove the need for invasive mediastinal staging in central or larger tumours — follow the multidisciplinary pathway.
The classic misread
- Calling post-obstructive collapse part of the tumour — separate tumour from atelectasis, ideally on PET or contrast enhancement.