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Mediastinal staging in lung cancer — PET-CT, EBUS and mediastinoscopy
Before resecting a lung cancer one must know whether the mediastinal nodes are involved (N2 or N3); PET-CT is the mandatory first step, and invasive staging — first EBUS or EUS with needle aspiration, then mediastinoscopy if negative and suspicion stays high — is needed when nodes are enlarged or avid, the tumour is central or larger than 3 cm, or N1 is suspected.
Why it matters in the exam
The exam likes to show a patient with a lung mass and ask "what is the next step". The answer depends on three things: what CT and PET show in the nodes, where the tumour is and how large it is. A peripheral tumour up to 3 cm with normal nodes on CT and PET can go straight to surgery; every other situation needs invasive staging. According to ESTS, endosonography (EBUS-TBNA, sometimes combined with EUS-FNA) is the first test because it is less invasive and reaches many stations; if it is negative but suspicion remains high, confirmatory mediastinoscopy follows, because endosonography has a non-negligible false-negative rate.
It is important to know which stations each test reaches: cervical mediastinoscopy reaches stations 2R, 2L, 4R, 4L and 7, but not the aortopulmonary window (stations 5 and 6), which is reached by anterior mediastinotomy (Chamberlain) or left VATS. EBUS reaches stations 2, 4, 7 and the hilar nodes 10 and 11; EUS through the oesophagus reaches stations 7, 8 and 9 and node 4L, as well as the left adrenal gland. In the 9th edition TNM (2024) N2 is split into N2a (single station) and N2b (multiple stations), a split that affects prognosis. A patient with proven N2 is not a candidate for primary surgery, and a patient with N3 is not a surgical candidate at all.
In addition, from stage II upward brain MRI is done to exclude metastases before surgery.
Key points
- PET-CT for every surgical candidate.
- Invasive staging for suspicious nodes, a central tumour or one larger than 3 cm.
- EBUS first, mediastinoscopy to confirm.
- Stations 5 and 6 — anterior mediastinotomy or VATS.
- Proven N2 — no primary surgery; N3 — no surgery.
Summary table
| Test | Stations reached | When |
|---|---|---|
| PET-CT | Whole body | Every resection candidate |
| EBUS-TBNA | 2, 4, 7, 10, 11 | First invasive test |
| EUS-FNA | 4L, 7, 8, 9, left adrenal | Complements EBUS |
| Cervical mediastinoscopy | 2R, 2L, 4R, 4L, 7 | Confirmation after negative endosonography with high suspicion |
| Anterior mediastinotomy or VATS | 5, 6 | Left upper lobe tumour with suspicion in the aortopulmonary window |
A free exam question
במהלך מדיאסטינוסקופיה נלקחה ביופסיה מבלוטת לימפה בתחנה 10 R . מיד לאחר מכן הופיע דימום מוגבר. מהו מקור הדימום הסביר ביותר? (the question as examined, in Hebrew)
- א. וריד הנבוב העליון
- ב. וריד האזיגוס
- ג. עורק ללא שם- INOMINATE
- ד. עורק ברונכיאלי ימני
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Sources
- ESTS guidelines for preoperative lymph node staging for non-small cell lung cancer, 2014 — Revised algorithm for invasive mediastinal staging
- IASLC TNM classification of lung cancer, 9th edition (2024) — N descriptors
- NCCN Clinical Practice Guidelines in Oncology: Non-Small Cell Lung Cancer, 2025 — Principles of Diagnostic Evaluation
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.