Lung carcinoma: spread and paraneoplastic syndromes
- Topic
Lung cancer causes trouble by local invasion (nerves, veins, pleura), by metastasis (brain, bone, liver, adrenals) and by hormones it makes.
What it is
Lung carcinomas spread to hilar and mediastinal nodes in most cases, invade neighbouring structures and metastasise widely, especially to adrenals, liver, brain and bone. Local invasion produces named syndromes such as Pancoast tumour, Horner syndrome and superior vena cava obstruction. Many tumours, especially small cell carcinoma, secrete hormones or trigger antibodies that cause paraneoplastic syndromes.
Structure
- Nodes: hilar, mediastinal and supraclavicular involvement by tumour (Virchow node on the left).
- Distant: adrenals (in a large share of cases), liver, brain and bone (often lytic).
- Pleural spread: malignant effusion with tumour cells in cytology.
- Staging uses the TNM system: T (size, invasion), N (nodal stations), M (distant spread).
Step by step
- The tumour grows through the bronchial wall into the lung, pleura and mediastinum.
- Apical tumours reach the brachial plexus and cervical sympathetic chain; central tumours compress the superior vena cava and nerves.
- Lymphatic spread fills hilar and mediastinal nodes; blood spread seeds adrenals, liver, brain and bone.
- Neuroendocrine cells of small cell carcinoma secrete ADH and ACTH.
- Squamous cells secrete PTH-related peptide, which raises calcium by bone resorption.
- Tumour antigens shared with neurons or muscle provoke autoantibodies (Lambert–Eaton, encephalitis).
Paraneoplastic syndromes of lung cancer
| Syndrome | Cause | Usual tumour type |
|---|---|---|
| SIADH (hyponatraemia) | Ectopic ADH | Small cell |
| Cushing syndrome | Ectopic ACTH | Small cell (also carcinoid) |
| Lambert–Eaton myasthenic syndrome | Antibodies to presynaptic calcium channels | Small cell |
| Hypercalcaemia | PTH-related peptide | Squamous cell |
| Hypertrophic osteoarthropathy and clubbing | Uncertain; growth factors | Non-small cell, mainly adenocarcinoma |
Clinical notes
- Stage is the main determinant of prognosis; many patients present with advanced disease.
- A smoker with new hyponatraemia, Cushingoid features or proximal weakness improving with repeated effort should be investigated for small cell carcinoma.
- A patient with shoulder pain, hand weakness and Horner syndrome may have a Pancoast tumour.
Test yourself
Think of the answer, then tap the question to see it.
What is a Pancoast tumour and what can it cause?
An apical (superior sulcus) lung tumour that invades the brachial plexus and sympathetic chain, causing arm and shoulder pain and Horner syndrome.
Which lung cancer type classically causes hypercalcaemia, and how?
Squamous cell carcinoma, by secreting PTH-related peptide.
Which three paraneoplastic syndromes are typical of small cell carcinoma?
SIADH, ectopic ACTH Cushing syndrome and Lambert–Eaton myasthenic syndrome.
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Small Cell Lung Cancer (StatPearls (NCBI Bookshelf), 2025); Non–Small Cell Lung Cancer (StatPearls (NCBI Bookshelf), 2025).
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Representative model, for educational purposes only.