The role of prophylactic cranial irradiation in patients with limited-stage small cell lung cancer at different risks of brain metastasis: A multicenter retrospective study

Background and purpose: To evaluate the value of prophylactic cranial irradiation (PCI) in patients with limitedstage small cell lung cancer (LS-SCLC) at different risks of brain metastasis (BM). Materials and methods: A retrospective study included 498 LS-SCLC patients from three centers who achieved complete or partial response (CR/PR) after radical chemoradiotherapy. A nomogram was developed using significant factors associated with BM, identified through univariate and multivariate analyses. Patients were stratified into high- and low-risk groups based on risk scores. The incidence of BM was compared between patients with and without PCI in different risk-stratified populations using the log-rank test. Results: The nomogram included age, start of treatment to the end of radiotherapy (SER), hemoglobin, prognostic nutritional index (PNI), ProGRP, and NSE. The area under the receiver operating characteristics (AUC) of the nomogram for predicting the 2-year probability of intracranial progression-free survival (IPFS) were 0.738, 0.811, and 0.726 in the training, internal validation, and external validation cohorts, respectively. In the low-risk group, no significant differences were observed in BM incidence (p = 0.220), OS (p = 0.679), or PFS (p = 0.616) between PCI and non-PCI groups. In the high-risk group, PCI significantly reduced BM incidence (p < 0.0001) and improved PFS (p = 0.032), while no significant differences were found in OS (p = 0.778). Propensity scorematching analysis showed similar results. Conclusion: PCI did not improve OS in patients regardless of high or low risk of BM. However, PCI did significantly reduce the incidence of BM and prolong PFS in patients at a high risk of BM.