## TNM Staging of Lung Cancer **Key Point:** TNM staging in NSCLC requires accurate assessment of tumour size (T), nodal involvement (N), and distant metastases (M). The 8th edition AJCC staging is the current standard. ### T-Stage Classification | T-Stage | Criteria | |---------|----------| | T1a | ≤1 cm | | T1b | 1–2 cm | | T1c | 2–3 cm | | T2a | 3–4 cm | | T2b | 4–5 cm | | T3 | 5–7 cm or invasion of pleura/chest wall | | T4 | >7 cm or invasion of mediastinum/heart/great vessels | ### N-Stage Classification | N-Stage | Criteria | |---------|----------| | N0 | No regional lymph node metastasis | | N1 | Ipsilateral peribronchial and/or hilar lymph nodes | | N2 | Ipsilateral mediastinal and/or subcarinal lymph nodes | | N3 | Contralateral or supraclavicular/scalene nodes | ### Case Analysis 1. **Tumour size:** 4 cm → **T2a** (3–4 cm range) 2. **Nodal involvement:** Ipsilateral hilar lymphadenopathy (short axis 1.8 cm) → **N1** (ipsilateral hilar nodes) 3. **Distant metastases:** PET-CT negative → **M0** **TNM: T2a N1 M0 = Stage IIIA** ### Stage Grouping (8th Edition AJCC) | Stage | T | N | M | |-------|---|---|---| | IA | T1a–T1c | N0 | M0 | | IB | T2a | N0 | M0 | | IIA | T1a–T1c | N1 | M0 | | IIB | T2b, T2a–T2b | N0, N1 | M0 | | IIIA | T1a–T1c, T2a–T2b, T3 | N1, N2 | M0 | | IIIB | T1a–T1c, T2a–T2b, T3, T4 | N2, N3 | M0 | | IIIC | T3, T4 | N3 | M0 | | IVA | Any T | Any N | M1a, M1b | | IVB | Any T | Any N | M1c | **High-Yield:** Hilar node involvement (N1) with a T2a tumour places this patient in **Stage IIIA**, which is locally advanced disease. This patient is a candidate for concurrent chemoradiation or neoadjuvant therapy followed by surgery if resectable. **Clinical Pearl:** The distinction between N1 (hilar) and N2 (mediastinal) is critical for prognosis and treatment planning. N1 disease has better outcomes than N2, but both are considered locally advanced. 
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