Efficacy evaluation of prophylactic cranial irradiation for limited stage small-cell lung cancer in the magnetic resonance imaging era: A meta-analysis

The role of prophylactic cranial irradiation (PCI) in patients with limited-stage small-cell lung cancer (LS-SCLC) remains controversial in the era of magnetic resonance imaging (MRI). The present study aimed to evaluate the effectiveness of PCI in the treatment of LS-SCLC in the era of MRI. The PubMed, EMBASE and Cochrane Library databases were searched from the time of database creation until May 24, 2023, to identify clinical studies that evaluated the effectiveness of PCI in patients with LS-SCLC in the MRI era. The references of the obtained studies were also reviewed to identify clinical studies that were not discovered in the initial search. All studies were screened in accordance with the inclusion criteria, and the data were extracted and subjected to meta-analysis using STATA17.0. In total, 21 studies were included in the analysis. Notably, 10 studies only used brain MRI at baseline to confirm the absence of brain metastases (BMs; pre-chemoradiotherapy MRI group), 7 studies used brain MRI prior to PCI to confirm the absence of BMs (pre-PCI MRI group) and 4 studies used active surveillance in the form of brain MRI following PCI (MRI surveillance group). The results of the meta-analysis demonstrated that for all included patients, PCI was associated with a significant improvement in overall survival time [OS; hazard ratio (HR), 0.61; confidence interval (CI), 0.53-0.70] and progression-free survival (HR, 0.69; CI, 0.61-0.79), as well as a significant decrease in the rate of BM (HR, 0.59; CI, 0.50-0.70). Subgroup analyses revealed that PCI remained effective in improving OS and reducing the rate of BM in patients with LS-SCLC who did not have BMs confirmed via brain MRI performed at baseline or prior to PCI. However, in the MRI surveillance group, PCI failed to significantly improve the OS (HR, 0.65; CI, 0.41-1.05), despite significantly reducing the BM rate (HR, 0.6; CI, 0.45-0.8) of LS-SCLC. Collectively, the results of the present study demonstrated that PCI remained effective in improving OS and reducing the rate of BM in patients with LS-SCLC who had the absence of BM confirmed via brain MRI at baseline or prior to PCI. Additionally, in patients with LS-SCLC who had undergone active surveillance using brain MRI following PCI, the incidence of BM was reduced, while the OS was not significantly improved. However, additional randomized controlled clinical studies are required to verify these findings.