Progress in radiotherapy for small‐cell lung cancer

Small‐cell lung cancer (SCLC) is a highly aggressive neuroendocrine tumor that is prone to spread extensively. Compared to non‐small‐cell lung cancer (NSCLC), SCLC treatment progresses slowly. Although SCLC is highly sensitive to chemotherapy during the initial treatment, most patients still experience resistance and recurrence after receiving chemotherapy. A meta‐analysis demonstrated that thoracic radiotherapy (TRT) improves overall survival in SCLC. The results of the CALGB and CONVERT trials provide evidence for the efficacy of once‐daily high‐dose TRT. TRT at 60 Gy administered twice daily significantly improved survival without increasing toxicity. The long‐standing debate over the optimal timing of radiotherapy has not been fully resolved. SBRT has excellent local control rates and is a safe and effective treatment option for patients with stage I or II SCLC. Prophylactic cranial irradiation (PCI) is used to reduce treatment‐related neurotoxicity to the extent that there has been a recent discussion on whether magnetic resonance imaging (MRI) monitoring can replace PCI. Radiotherapy combined with immunotherapy significantly improves the survival rate of patients with NSCLC; however, its clinical effectiveness has not been systematically explored in patients with SCLC. Therefore, we summarize the evolving therapeutic strategies, (TRT for limited stage‐SCLC and consolidative TRT for extensive stage‐SCLC) and improved radiotherapy techniques (role of SBRT in stage I or II node‐negative SCLC, progress of PCI, and stereotactic radiosurgery), and discuss the possibilities and prospects of radiotherapy combined with immunotherapy for SCLC.