Lung Cancer Staging: TNM Chart and Stages 0 to IV (Version 9)
Lung cancer is staged from 0 to IV by the size and reach of the tumor (T), the lymph nodes involved (N) and any distant spread (M). Since January 2025, US lung cancers are staged with AJCC Version 9, which splits N2 into N2a and N2b and M1c into M1c1 and M1c2. Small cell lung cancer is also described as limited or extensive stage.
Staging is how doctors describe where a cancer is. It helps your team choose treatment and explain what to expect. New to these terms? Start with our guide to cancer stages or the TNM staging reference. For the disease itself, see our lung cancer guide.
What changed in Version 9
The American Joint Committee on Cancer (AJCC) moved lung cancer to Version 9 in 2025. The T categories did not change. Two categories were split, and some stage groups moved.
- N2 became N2a and N2b. N2 means cancer in lymph nodes in the middle of the chest on the same side as the tumor. N2a means one group (station) of these nodes. N2b means more than one.
- M1c became M1c1 and M1c2. Both mean several tumors outside the chest. M1c1 means they are in one organ system. M1c2 means more than one organ system. Both are still stage IVB.
| TNM | 8th edition | Version 9 |
|---|---|---|
| T1 N1 M0 | IIB | IIA |
| T1 N2 M0 | IIIA | IIB if N2a, IIIA if N2b |
| T2 N2 M0 | IIIA | IIIA if N2a, IIIB if N2b |
| T3 N2 M0 | IIIB | IIIA if N2a, IIIB if N2b |
Reading an older report. If you were diagnosed before 2025, your report probably uses the 8th edition. That stage is not wrong. It was correct for its time. You usually cannot convert it yourself, because the old N2 does not say how many node stations were involved. Ask your team which edition your stage uses before you compare it with this chart.
T: the main tumor
T describes tumor size and what the tumor has grown into. For scale, 3 cm is a little over 1 inch.
| T | What it means |
|---|---|
| TX | The main tumor cannot be assessed, or cancer cells appear in mucus or airway washings but no tumor shows on scans or bronchoscopy (a camera passed into the airways). |
| T0 | No sign of a main tumor. |
| Tis | Carcinoma in situ: abnormal cells that have not invaded deeper tissue. |
| T1mi | Minimally invasive adenocarcinoma: 3 cm or smaller, with 5 mm or less of invasion. |
| T1a | 1 cm or smaller. Also an uncommon surface tumor of any size that is limited to the airway wall. |
| T1b | Over 1 cm, up to 2 cm. |
| T1c | Over 2 cm, up to 3 cm. |
| T2a | Over 3 cm, up to 4 cm. Or 4 cm or smaller and any of these: it invades the thin lining of the lung (visceral pleura) or an adjacent lobe, involves the main bronchus but not the carina (where the windpipe divides), or causes collapse or inflammation of part or all of the lung. |
| T2b | Over 4 cm, up to 5 cm. |
| T3 | Over 5 cm, up to 7 cm. Or 7 cm or smaller and any of these: it invades the chest wall or outer lining of the lung (parietal pleura), the sac around the heart (pericardium), the phrenic nerve or azygos vein, or there are separate tumor nodules in the same lobe. |
| T4 | Over 7 cm. Or any size and it invades the mediastinum (the space between the lungs), heart, great vessels, windpipe, carina, esophagus, diaphragm, spine or major nerves, or there are separate nodules in a different lobe of the same lung. |
N: nearby lymph nodes
Lymph nodes are small glands that filter fluid. The chest nodes are mapped into numbered areas called stations. "Same side" below means the same side as the tumor.
| N | What it means |
|---|---|
| NX | Nodes cannot be assessed. |
| N0 | No cancer in regional lymph nodes. |
| N1 | Cancer in nodes in or at the root of the lung (peribronchial, hilar or intrapulmonary) on the same side. |
| N2a | Cancer in a single mediastinal station on the same side, or in the subcarinal station (nodes below where the windpipe divides). |
| N2b | Cancer in more than one mediastinal station on the same side, with or without the subcarinal station. |
| N3 | Cancer in mediastinal or hilar nodes on the opposite side, or in scalene or supraclavicular nodes (near the collarbone) on either side. |
M: distant spread
| M | What it means |
|---|---|
| M0 | No distant spread found. |
| M1a | Tumor nodules on the lining of the lung or heart, cancer in the fluid around the lung or heart, or separate nodules in the other lung. |
| M1b | A single tumor outside the chest, in one organ system. This includes one distant lymph node. |
| M1c1 | Several tumors outside the chest in one organ system. The skeleton counts as one organ system. |
| M1c2 | Several tumors outside the chest in more than one organ system. |
Lung cancer stage chart (Version 9)
Find your T and N together. All rows from occult to IIIC are M0.
| Stage | T and N combinations |
|---|---|
| Occult | TX N0 |
| 0 | Tis N0 |
| IA1 | T1mi N0, T1a N0 |
| IA2 | T1b N0 |
| IA3 | T1c N0 |
| IB | T2a N0 |
| IIA | T2b N0, T1 N1 |
| IIB | T3 N0, T2 N1, T1 N2a |
| IIIA | T4 N0, T3 N1, T4 N1, T1 N2b, T2 N2a, T3 N2a |
| IIIB | T2 N2b, T3 N2b, T4 N2a, T4 N2b, T1 N3, T2 N3 |
| IIIC | T3 N3, T4 N3 |
| IVA | Any T, any N, M1a or M1b |
| IVB | Any T, any N, M1c1 or M1c2 |
Your report may also carry a small letter in front of the code. A "c" means the stage came from exams and scans. A "p" means it came from tissue removed at surgery. A "yp" means it came from tissue removed after treatment given before surgery. See TNM prefixes for the full list.
Small cell lung cancer: limited and extensive stage
Small cell lung cancer tends to grow and spread faster than non-small cell lung cancer, and in most people it has already spread beyond the lungs at diagnosis. Version 9 recommends TNM for it too, but doctors still often use two simpler terms, because they match the main treatment decision.
| Limited stage | Extensive stage | |
|---|---|---|
| Where the cancer is | One side of the chest, the middle of the chest or the nodes above the collarbone, and it fits in one tolerable radiation field | Beyond that area, or too widespread for one radiation field. Any distant spread (M1) is extensive stage |
| Rough TNM match | Stages I to IIIB with no distant spread | Stage IV |
| Share at diagnosis | About 1 in 3 | About 2 in 3 |
| Usual treatment | Chemotherapy with radiation, aiming for cure | Chemotherapy with immunotherapy, aiming for control |
There is no single universal definition of limited stage. Doctors differ on some borderline situations, such as nodes above the collarbone on the opposite side. Cancer cells in the fluid around the lung count as M1 and so as extensive stage.
Tests used to stage lung cancer
- CT scan: shows the tumor's size and position, and enlarged lymph nodes.
- PET/CT scan: shows whether and where the cancer has spread.
- Brain MRI: checks for spread to the brain.
- EBUS and EUS: ultrasound on a thin tube passed through the airway (EBUS) or esophagus (EUS). The doctor can take a biopsy of chest lymph nodes at the same time. This is how node stations are often counted.
- Mediastinoscopy: a surgical procedure to sample nodes behind the breastbone.
- Thoracentesis: a needle drains fluid from around the lung to look for cancer cells.
Biomarker testing looks for gene changes and proteins in the tumor. It does not set the stage, but it can decide which targeted therapy or immunotherapy fits. Ask for it if you have stage IV disease and have not heard the results.
What each stage usually means for treatment
This is a general picture of non-small cell lung cancer, based on American Cancer Society guidance. Your plan depends on your tumor, lung function and overall health.
| Stage | Typical approach |
|---|---|
| 0 | Surgery alone is usually curative. |
| I | Surgery, usually removing a lobe. Stereotactic radiation (precise, high-dose beams) if surgery is not possible. Some higher-risk patients get added treatment after surgery. |
| II | Often chemotherapy, with or without immunotherapy, before surgery. More treatment may follow. |
| IIIA | A team plan combining radiation, chemotherapy, immunotherapy and sometimes surgery. |
| IIIB, IIIC | Usually not removable by surgery. Often chemotherapy with radiation, then durvalumab, or osimertinib if the tumor has an EGFR change. |
| IVA | A single distant site may be treated directly with surgery or radiation, along with treatment for the lung tumor. |
| IVB | Targeted therapy if a matching gene change is found. Otherwise immunotherapy alone or with chemotherapy. The aims are longer life and fewer symptoms. |
Palliative care helps with breathlessness, pain and worry at any stage, alongside treatment. Read more in what stage 4 cancer means.
Lung cancer survival by stage
US figures are reported with SEER stages (localized, regional, distant), not stages I to IV. These are 5-year relative survival rates, which compare people with cancer to similar people in the general population. They come from people treated years ago.
| SEER stage | All lung (2016 to 2022) | Non-small cell (2015 to 2021) | Small cell (2012 to 2018) |
|---|---|---|---|
| Localized | 65.5% | 67% | 34% |
| Regional | 38.2% | 40% | 20% |
| Distant | 10.5% | 12% | 4% |
| All stages | 29.5% | 32% | 9% |
These numbers cannot tell you what will happen to you. The American Cancer Society reports that distant-stage lung cancer survival rose from 2% in the mid-1990s to 10%, and newer treatments may not be fully reflected yet. Our guide to prognosis and survival rates explains how to read these figures.
Call your care team now if you cough up blood, your breathing suddenly gets worse, your face or neck swells, you have new weakness or numbness, or you have a fever of 100.4°F (38°C) or higher during treatment. See when to call your doctor. Go to the emergency room or call 911 if you are struggling to breathe.
Frequently asked questions
What is the difference between N2a and N2b in lung cancer?
Both mean cancer has reached lymph nodes in the middle of the chest on the same side as the tumor. N2a means a single node station. N2b means more than one station. The split matters because it can change the stage: T1 N2a is stage IIB, while T1 N2b is stage IIIA.
My report uses the 8th edition. Is my stage wrong?
No. Cancers diagnosed before 2025 were usually staged with the 8th edition, and that stage was correct at the time. Your original stage normally stays on your record. A few groups are different in Version 9, so ask your team which edition applies before comparing your report with a Version 9 chart.
Is M1c1 worse than M1c2?
Both are stage IVB. M1c1 means several tumors outside the chest in one organ system, and M1c2 means several tumors in more than one organ system. The stage is the same, and treatment still depends mostly on the tumor's biomarkers and your health.
Does a lung nodule in the other lung make it stage 4?
A separate tumor nodule in the other lung is usually classed as M1a, which is stage IVA. Ask your team how they have classed it and why.
What does stage 3 lung cancer treatment involve?
Stage III usually means a team plan. It often combines chemotherapy, radiation and immunotherapy, and some stage IIIA cancers also have surgery. Stage IIIB and IIIC cancers usually cannot be fully removed by surgery. Ask your doctor directly whether the goal of your treatment is cure or control.
Does the stage change if lung cancer spreads later?
The stage given at diagnosis stays the same on your record, even if the cancer later grows or comes back. Survival statistics also apply to the stage at first diagnosis.
Is limited stage small cell lung cancer curable?
Limited stage small cell lung cancer is treated with chemotherapy and radiation with the aim of cure. Your team can explain your own chances.
Sources
- FACS: AJCC Current Staging System table (2026)
- National Cancer Institute: Non-Small Cell Lung Cancer Treatment (PDQ), health professional version
- National Cancer Institute: Small Cell Lung Cancer Treatment (PDQ), health professional version
- American Cancer Society: Non-Small Cell Lung Cancer Stages
- American Cancer Society: Small Cell Lung Cancer Stages
- American Cancer Society: How Lung Cancer Is Diagnosed and Staged
- American Cancer Society: Treatment Choices for Non-Small Cell Lung Cancer, by Stage
- American Cancer Society: What Is Lung Cancer?
- American Cancer Society: Lung Cancer Survival Rates
- SEER: Cancer Stat Facts, Lung and Bronchus Cancer
- American Cancer Society: Cancer Statistics 2026 press release
- Radiopaedia: Lung cancer staging (IASLC 9th edition)
This page is general information, not medical advice. Your care team knows your situation and should guide your decisions.