Lung Cancer Stages Explained: From Stage 0 to Stage IV

Lung cancer staging tells your care team how far the disease has spread and drives every treatment decision. It also gives you and your family a realistic sense of what to expect. Modern staging is more precise than ever — and modern treatments have changed outcomes at every stage, especially the advanced ones.

Two main types: NSCLC and SCLC

About 85% of lung cancers are non-small cell lung cancer (NSCLC): adenocarcinoma, squamous cell carcinoma, or large cell carcinoma. The remaining 15% are small cell lung cancer (SCLC), which grows faster and is treated differently. Both use their own staging, but NSCLC follows the TNM system described below.

The TNM system

• T (tumor): size and local invasion (T1–T4)
• N (nodes): whether cancer is in lymph nodes and which ones (N0–N3)
• M (metastasis): whether cancer has spread to distant organs (M0 or M1)

These three letters combine into an overall stage (I–IV).

Stage 0 — carcinoma in situ

Cancer cells are confined to the top layer of the airway lining. Surgery or bronchoscopic removal is curative in almost all cases.

Stage I — localized, no lymph nodes

Tumor is small (≤4 cm) and hasn't reached lymph nodes. Standard treatment is surgery (lobectomy). For patients who can't have surgery, stereotactic body radiotherapy (SBRT) achieves comparable outcomes. Five-year survival: 68–92%.

Stage II — larger tumor or spread to nearby nodes

Tumor is larger (4–7 cm) or has spread to hilar lymph nodes on the same side. Treatment is surgery followed by adjuvant chemotherapy (and sometimes immunotherapy). Five-year survival: 53–60%.

Stage III — locally advanced

Cancer has spread more extensively within the chest — to mediastinal nodes (N2 or N3) or invaded nearby structures. Stage III is split into IIIA, IIIB, and IIIC based on complexity. Treatment usually combines chemotherapy, radiation, and (since 2020s) immunotherapy (durvalumab after chemoradiation is now standard). Five-year survival has risen to 26–36% — much better than a decade ago.

Stage IV — metastatic

Cancer has spread to the other lung, distant lymph nodes, or other organs (brain, liver, bones, adrenals). Cure is uncommon, but stage IV is where the biggest breakthroughs are happening. Molecular testing is essential — if your tumor has an EGFR, ALK, ROS1, KRAS G12C, or other actionable mutation, targeted therapy pills can control disease for years. For tumors without a driver mutation, immunotherapy alone or combined with chemotherapy has extended median survival from 12 months (a decade ago) to 22–30 months. Some patients live 5+ years.

What survival numbers actually mean

Published five-year survival statistics are averages built from patients diagnosed 5–10 years ago. They don't reflect this year's therapies. If you were just diagnosed, your outlook is likely better than the chart. What matters most: your specific subtype, your biomarkers, your fitness, and the team treating you.