Lung cancer
Description
The primary division: small cell vs non-small cell
| NSCLC (~85%) | SCLC (~15%) | |
|---|---|---|
| Behaviour | Local then regional then distant | Disseminated at presentation in ~2/3 |
| Surgery | Cornerstone in early stage | Almost never |
| Driver mutations | Common in adenocarcinoma | Essentially none actionable |
| Chemo/RT sensitivity | Moderate | Exquisite, but relapses |
| Paraneoplastic | Hypercalcaemia (SCC), HPOA | SIADH, ectopic ACTH, LEMS, encephalomyelitis |
NSCLC subtypes
- Adenocarcinoma (~40%, and rising) - the commonest subtype in Australia
- Peripheral; the subtype in never-smokers, women, Asian ancestry
- Most likely to carry a targetable driver (EGFR, ALK, ROS1, RET, MET, BRAF, KRAS G12C, NTRK, HER2)
- TTF-1 and napsin A positive
- Squamous cell (~25-30%) - central, cavitates, strongly smoking-related
- PTHrP -> hypercalcaemia; p40/p63/CK5-6 positive
- Large cell / neuroendocrine (~5-10%)
- Carcinoid - low grade neuroendocrine; young, non-smokers; carcinoid syndrome is rare from a lung primary without liver metastases
SCLC
- Central, bulky mediastinal nodal disease, rapid doubling time, near-universally in heavy smokers
- Neuroendocrine markers: chromogranin, synaptophysin, CD56, high Ki-67 (>50-90%)
- Limited stage (confinable to one tolerable radiotherapy port) vs extensive stage
Named presentations
- Pancoast (superior sulcus) tumour - apical; shoulder/arm pain (C8-T1), Horner syndrome, small muscle wasting of the hand, rib destruction
- SVC obstruction - facial and arm swelling, distended non-pulsatile neck veins, Pemberton sign
- Lambert-Eaton myasthenic syndrome - SCLC; proximal weakness that improves with repetition, absent reflexes that return after exercise, autonomic features
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