Immunotherapy Improves Survival Prognosis and Reduces the Risk of Brain Metastasis in Limited-stage Small Cell Lung Cancer Patients Receiving Prophylactic Cranial Irradiation

The 1-year and 3-year BM rates after PCI were 11.3% and 28.3%, respectively. Survival analysis revealed that the immunotherapy group had significantly prolonged OS (mOS: 38.0 months vs 27.0 months, p=0.019) and a significantly lower 3-year BM rate (10.8% vs 31.7%, p=0.035). Subgroup analysis based on the timing of immunotherapy relative to PCI showed that only patients receiving immunotherapy before PCI demonstrated more significant OS benefit (mOS: 40.0 months vs 27.0 months, p=0.007) and a lower BM risk (3-year BM rate: 7.7% vs 31.7%, p=0.047) compared to the non-immunotherapy group.

For patients who started immunotherapy after PCI, there were no statistically significant differences in OS or BM risk compared to the non-immunotherapy group. Multivariate analysis identified immunotherapy (HR=0.48, p=0.008), smoking history (HR=0.46, p=0.004), and extracranial metastasis (HR=1.92, p=0.012) as independent factors affecting OS. Immunotherapy (HR=0.25, p=0.019) and smoking history (HR=0.20, p=0.008) were independent factors influencing BM risk.Conclusion For LS-SCLC patients receiving PCI, early combination with immunotherapy, particularly before PCI, can effectively reduce the incidence of brain metastasis and significantly prolong survival.

Furthermore, smoking history is a significant adverse risk factor affecting patient prognosis and should be emphasized in clinical management.