Lung cancer comprises a group of malignant tumours arising from the epithelial lining of the lower respiratory tract and is subdivided into small cell and non-small cell categories based on histological findings.
Small cell lung cancer (SCLC) is an aggressive malignancy. Approximately two-thirds of patients have evidence of distant metastasis at presentation.
Primarily develops in older adult smokers.
Most common presenting symptoms are cough, chest pain, haemoptysis, dyspnoea, and weight loss.
A suspicious lung mass should be biopsied during bronchoscopy or CT-guided transthoracic needle aspiration.
Staging studies should include chest/abdomen CT and brain MRI (preferred) or head CT, with mediastinoscopy and/or bone marrow aspirate and biopsy in selected cases. If disease appears to be confined to the chest, positron emission tomography (PET)-CT can be done to assess for distant metastases. Bone scan can be done if PET-CT is not available. Accurate staging is very important for treatment selection.
Localised disease (defined as disease that can be contained within a radiation portal) should be treated with concurrent chemotherapy and radiotherapy. Radiotherapy should be started as early as possible. Surgery should be offered to patients with clinical T1N0 or T2N0 disease after mediastinoscopy. Extensive-stage disease should be treated with chemotherapy. Palliative radiotherapy may be utilized if necessary. Prophylactic cranial irradiation should be considered for all patients who demonstrate a response to initial therapy and are stable at completion of therapy.
Small cell lung cancer (SCLC), previously referred to as oat cell carcinoma, is a malignant epithelial tumour arising from cells lining the lower respiratory tract. The tumour cells are small and densely packed, with scant cytoplasm, finely granular nuclear chromatin, and absence of nucleoli. 
Assistant Professor of Medicine
Harvard Medical School
Massachusetts General Hospital
RSH has received honoraria for consulting from Boehringer-Ingelheim and Ariad.
Dr Rebecca Suk Heist would like to gratefully acknowledge Dr Leena Gandhi, Dr Alvin R. Cabrera, Dr Christopher R. Kelsey, and Dr Lawrence B. Marks, previous contributors to this monograph. LG, ARC, CRK, and LBM declare that they have no competing interests.
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