Small cell lung cancer (SCLC), as a pathological type with high malignancy, presents a high risk of early brain metastasis. Prophylactic cranial irradiation (PCI) can reduce the risk of brain metastasis in patients with SCLC, however, the incidence of brain structural and functional damage caused by PCI is high, and their clinical symptoms are not typical. The existing treatment methods can relieve some clinical symptoms, but can not effectively reverse the process of brain injury, which reduces the survival benefit of patients. In-depth understanding the mechanisms of PCI neurotoxicity and exploring effective strategies for ptevention and treatment are of great value in improving prognosis of SCLC.