A prospectively-collected database of 371 patients with extensive-stage small cell lung cancer without baseline brain metastases reports chemoimmunotherapy improved overall survival but did not reduce the incidence of subsequent brain metastases, with roughly one-quarter of patients developing intracranial disease peaking around 8 months after treatment initiation. Prophylactic cranial irradiation (PCI) was the only intervention independently associated with a lower risk of brain metastasis (HR 0.43), reinforcing that PCI remains the only evidence-based strategy for CNS prevention in the immunotherapy era. When PCI is omitted, these data support vigilant MRI surveillance during the two years of diagnosis when early detection may enable radiosurgery for limited intracranial disease and delay the need for whole brain radiation. | Cao, JCO Oncol Pract 2026
