This is a clinical practice guideline for patients with small cell lung cancer. The guideline examines the diagnosis, staging, prognostic factors, treatment, and surveillance of these patients. Treatment options discussed include systemic therapy, radiotherapy, and surgical resection. Systemic therapy is further examined in elderly patients, and as a second-line (and beyond) treatment. Radiotherapy treatments considered include thoracic radiotherapy, prophylactic cranial irradiation, and palliative radiotherapy.