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Small cell lung cancer
A very fast neuroendocrine tumour of smokers, highly sensitive at first to chemotherapy and radiation but quick to relapse; limited disease gets chemoradiation, and extensive disease gets platinum-etoposide with immunotherapy.
Why it matters in the exam
Small cell lung cancer appears in the exam almost every year. The stem shows a smoker with a central mass, mediastinal nodes and sometimes hyponatraemia or proximal muscle weakness, and asks about limited versus extensive disease, the standard treatment, prophylactic cranial irradiation (PCI) or the meaning of a high Ki-67. Second-line options and newer drugs such as a bispecific antibody are also asked. Remember that this is the tumour where even a patient with poor performance status may gain from chemotherapy, because the response is fast and dramatic.
This tumour has very rapid doubling and early spread, so almost two thirds of patients are diagnosed with extensive disease. The questions test whether the candidate understands why surgery hardly plays a role, why thoracic radiation is given early and concurrently with chemotherapy, and why brain surveillance matters so much.
Key points
- Small cell lung cancer is a central neuroendocrine tumour of smokers with a very high Ki-67.
- Limited disease: cisplatin-etoposide with concurrent thoracic radiation, followed by durvalumab.
- Extensive disease: platinum-etoposide with atezolizumab or durvalumab, then maintenance.
- PCI or close MRI surveillance after response lowers the danger of brain metastases.
- Associated syndromes: SIADH, ectopic ACTH and Lambert-Eaton.
Summary table
| Situation | Treatment | Note |
|---|---|---|
| Limited disease T1–T2 N0 (rare) | Surgery followed by chemotherapy | Mediastinal involvement must be excluded by invasive staging |
| Limited disease (within one radiation field) | Cisplatin-etoposide with early concurrent thoracic radiation | 45 Gy in 30 fractions twice daily, or 60 to 70 Gy once daily; then durvalumab |
| After response in limited disease | PCI of 25 Gy in 10 fractions, or close brain MRI surveillance | PCI reduces brain metastases; spare the hippocampus where possible |
| Extensive disease | Carboplatin-etoposide with atezolizumab or durvalumab, then maintenance immunotherapy | Thoracic radiation in good responders with low burden |
| Relapse | Topotecan, lurbinectedin or tarlatamab | Tarlatamab is a DLL3 and CD3 bispecific antibody; relapse after 6 months — platinum can be repeated |
| Paraneoplastic syndromes | Treating the tumour itself is the main treatment | SIADH with hyponatraemia, ectopic ACTH with hypokalaemia, Lambert-Eaton with proximal weakness |
| Patient with poor performance status | Chemotherapy is still considered, because the response is fast and may improve the condition | Shared decision, with emphasis on supportive care and quality of life |
In the full version for subscribers
- A simple algorithm
- Memory aid
- Exam traps
- 5 review cards
- Enough for IMLE
The full version is open to subscribers of: Oncology, Medical licensing exam (IMLE), Internal medicine.
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Sources
- NCCN Clinical Practice Guidelines in Oncology: Small Cell Lung Cancer, 2026 — Principles of systemic and radiation therapy
- ESMO Clinical Practice Guideline: Small-cell lung cancer, 2021 — Diagnosis, treatment and follow-up
- Gunderson and Tepper's Clinical Radiation Oncology, 5th ed. (2021) — Small cell lung cancer
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.