Surgical Specialties – Merrimack Thoracic & Esophageal Surgery

What does “TNM” mean?

Doctors describe lung cancer using three parts: T (the size/extent of the main Tumor), N (whether nearby lymph Nodes contain cancer), and M (whether the cancer has Metastasized, meaning spread to other organs). These are combined to assign an overall stage (I–IV).^{:contentReference[oaicite:0]{index=0}}

T: Primary Tumor

T1 – A small tumor (≤3 cm) limited to the lung. Subtypes T1a (≤1 cm), T1b (>1–2 cm), T1c (>2–3 cm).^{:contentReference[oaicite:1]{index=1}}
T2 – 3–5 cm or involves the main bronchus (not the carina), visceral pleura, causes atelectasis/pneumonitis; T2a (>3–4 cm) or T2b (>4–5 cm).^{:contentReference[oaicite:2]{index=2}}
T3 – 5–7 cm or invades chest wall/parietal pleura, pericardium, phrenic nerve, azygos vein, or has separate nodule(s) in the same lobe.^{:contentReference[oaicite:3]{index=3}}
T4 – >7 cm or invades mediastinum, diaphragm, trachea/carina, great vessels, vertebral body, esophagus, recurrent laryngeal or vagus nerves, or has separate nodule(s) in a different lobe on the same side.^{:contentReference[oaicite:4]{index=4}}

Your imaging and, when needed, bronchoscopy or surgery help determine T.

N: Lymph Nodes

N0 – No lymph nodes involved.^{:contentReference[oaicite:5]{index=5}}
N1 – Nodes inside the lung or near the main airway (hilar/intrapulmonary).^{:contentReference[oaicite:6]{index=6}}
N2a/N2b – Single or multiple stations in the central chest (ipsilateral mediastinal/subcarinal).^{:contentReference[oaicite:7]{index=7}}
N3 – Nodes on the other side of the chest or above the collarbone (contra- or supraclavicular).^{:contentReference[oaicite:8]{index=8}}

M: Metastasis

M0 – No spread outside the chest.^{:contentReference[oaicite:9]{index=9}}
M1a – Cancer in the other lung or cancerous fluid/nodules in the pleura/pericardium.^{:contentReference[oaicite:10]{index=10}}
M1b – A single spot in one organ outside the chest (e.g., liver, brain, bone) or a single non-regional lymph node.^{:contentReference[oaicite:11]{index=11}}
M1c1 – Multiple metastases within a single organ system (e.g., multiple liver lesions).^{:contentReference[oaicite:12]{index=12}}
M1c2 – Metastases in multiple organ systems (e.g., liver and bone).^{:contentReference[oaicite:13]{index=13}}

Stage Groups (I–IV)

After T, N, and M are known, they’re combined to assign an overall stage:

Stage I – Small and limited to the lung (no nodes, no spread).^{:contentReference[oaicite:14]{index=14}}
Stage II – Larger and/or some nearby lymph nodes.^{:contentReference[oaicite:15]{index=15}}
Stage III – More advanced lymph nodes or invasion into nearby structures (still potentially treatable with curative intent in select cases).^{:contentReference[oaicite:16]{index=16}}
Stage IV – Spread outside the chest (metastatic).^{:contentReference[oaicite:17]{index=17}}

Your care team will review imaging, biopsy results, and sometimes surgical findings to finalize staging.

Why Staging Matters

Treatment planning: guides surgery, radiation, chemotherapy, targeted therapy, and immunotherapy choices.
Prognosis: helps estimate likely outcomes and response to therapy.
Consistency: gives clinicians a shared language worldwide.^{:contentReference[oaicite:18]{index=18}}

Questions to Ask Your Team

What are my T, N, and M categories and overall stage?

Is my staging based on imaging alone, or is there surgical/pathology information?

What treatments fit my stage—and in what order?

Are there clinical trials appropriate for me?

About This Page

Content adapted to patient-friendly language from the International Association for the Study of Lung Cancer (IASLC) 9th Edition TNM updates and nodal maps.^{:contentReference[oaicite:19]{index=19}} This page does not replace medical advice specific to your case.

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Surgery Resources

Additional forms and documents that need to be reviewed

Resources

Lung Cancer Staging (TNM – 9th Edition)