Ninth-edition TNM staging
Accurate staging connects the diagnosis to the right treatment plan.
Staging describes where a lung cancer is located and how far it has spread. Our office reviews the imaging and pathology already completed, identifies missing information, and coordinates the next appropriate step.
Request a staging reviewCurrent framework
The ninth-edition TNM system
The ninth edition of lung-cancer TNM staging took effect January 1, 2025. It combines three kinds of information:
| Letter | What it describes |
|---|---|
| T — Tumor | The size of the lung tumor and whether it involves nearby structures. |
| N — Nodes | Whether cancer has reached lymph nodes within the lung, at the hilum, or in the mediastinum between the lungs. The current edition further distinguishes single-station from multiple-station N2 disease. |
| M — Metastasis | Whether cancer has spread to the other lung, the pleura or pericardium, or organs outside the chest. The current edition adds detail about whether multiple metastases involve one organ system or several. |
These findings form an overall stage. In broad terms:
- Stage I: usually confined to the lung without lymph-node spread.
- Stage II: may involve a larger or locally extending tumor or nearby N1 lymph nodes.
- Stage III: often involves mediastinal lymph nodes or more locally advanced disease.
- Stage IV: metastatic disease.
This page focuses primarily on non-small cell lung cancer. Small cell lung cancer may also be described as limited-stage or extensive-stage disease, although TNM information can still be useful.
How do we determine the stage?
Not every patient needs every test. The workup is selected according to the tumor, symptoms, available studies, and the decisions that the result could change.
- Diagnostic CT with contrast. CT evaluates the primary tumor, lymph nodes, and surrounding chest structures and usually extends through the upper abdomen to include the liver and adrenal glands.
- PET/CT. PET/CT looks for metabolically active disease in lymph nodes and elsewhere. Uptake does not prove cancer—infection and inflammation can also be active—and microscopic cancer may be present in a PET-negative node.
- Brain MRI when indicated. MRI may be obtained when symptoms, tumor features, or the apparent stage make brain spread a meaningful concern. PET/CT is not reliable for evaluating the brain.
- Biopsy and tissue confirmation. Imaging estimates the stage. Pathology establishes whether suspicious tissue contains cancer. When a lymph-node result could change treatment, tissue staging may be necessary.
A decision-changing step
Why mediastinal staging matters
The mediastinum contains lymph nodes between the lungs. Finding cancer in these nodes can change whether surgery, systemic treatment, radiation, or a combined approach is appropriate. Invasive staging is commonly considered when CT shows enlarged nodes, PET/CT shows suspicious nodal uptake, the tumor is centrally located, hilar nodes appear involved, or other features create a meaningful risk of hidden mediastinal disease.
| Procedure | Role |
|---|---|
| EBUS-TBNA | A bronchoscope with ultrasound identifies and samples lymph nodes through the airway. |
| EUS or EUS-B | Samples complementary lymph-node areas through the esophagus and may be combined with EBUS. |
| Mediastinoscopy | An operation that obtains lymph-node tissue through a small incision above the breastbone. It is used selectively when endoscopic staging is unavailable, incomplete, nondiagnostic, or does not adequately answer the clinical question. |
Clinical stage and pathologic stage
The clinical stage is assigned before treatment using imaging and biopsy results. If surgery is performed, examination of the removed tumor and lymph nodes provides the pathologic stage, which may refine the original estimate and guide decisions about treatment after surgery.
Staging is not a one-time label. New pathology, interval imaging, or a response to treatment can change the information used by the team.
Coordinated regional care
We connect the staging steps
We work with pulmonologists, radiologists, pathologists, medical oncologists, and radiation oncologists throughout the Merrimack Valley and Southern New Hampshire so that staging and treatment decisions are connected rather than fragmented.
Sources and further reading
Sources reviewed September 12, 2026. This brief outline is not an individualized recommendation or a substitute for current guidelines and multidisciplinary review.