Prophylactic cranial irradiation in ES-SCLC: The ongoing debate from the past to the immunotherapy Era"

SCLC (Small Cell Lung Cancer) is categorized into two stages: limited-stage (LS-SCLC), where the cancer is confined to a single radiation field, and extensive-stage, where the disease has spread beyond the chest, potentially including the brain. In managing extensive-stage SCLC (ES-SCLC), preventing brain metastases becomes a crucial goal, as these metastases are a major cause of mortality due to their severe complications. Prophylactic cranial irradiation (PCI) has been shown to reduce the incidence of brain metastases and, according to the pre-immunotherapy meta-analysis by Auperin et al., improve overall survival (OS). With the advent of chemoimmunotherapy in extensive-stage SCLC, the role of PCI is being re-evaluated, as immunotherapy may enhance systemic control, improve survival, and lower the risk of brain metastases, raising questions about the continued necessity of PCI. This review examines key studies that shaped prior guidelines and the evolving understanding of PCI's effectiveness in the current treatment landscape. It evaluates both studies supporting and questioning PCI's role, given the enhanced systemic control with immuno-chemotherapy, while also addressing the risks and long-term complications of PCI, including cognitive impacts and quality of life concerns. Additionally, the review explores alternative strategies, such as MRI surveillance, and identifies which patient populations are most likely to benefit from PCI and in which patients PCI can be omitted.