Objective: Prophylactic cranial irradiation (PCI) is a companion treatment option for small cell lung cancer (SCLC) patients. However, its efficacy and associated risk factors have not been clearly defined. In this study, the authors aimed to systematically assess the effectiveness and role of PCI in the treatment plan of SCLC.
Methods: The PubMed, Scopus, Web of Science, and Cochrane databases were searched using the following key terms and their equivalents: "brain," "radiotherapy," "metastases," "prophylactic," and "small cell lung cancer." Studies comparing overall survival (OS), progression-free survival (PFS), brain metastasis-free survival (BMFS), and incidence of brain metastases between patients receiving PCI and those not receiving it were considered eligible. Risk of bias was assessed using the Risk of Bias in Non-Randomized Studies-of Interventions (ROBINS-I) tool. Meta-analysis was conducted on the mentioned outcomes with subgrouping based on different factors.
Results: The authors identified 74 studies published between 1983 and 2022 with 31,551 SCLC patients, of whom 26.7% received PCI. The studies were a mix of prospective randomized and retrospective observational studies. Patients with limited-stage disease receiving PCI had better OS, PFS, and BMFS than those not receiving PCI. Patients receiving PCI also had significantly longer OS times and developed brain metastases significantly later. However, findings regarding extensive-stage SCLC were not as promising.
Conclusions: PCI is an effective option for limited-stage SCLC patients. It improves OS and PFS, delays brain metastases, and reduces the incidence of brain metastases. However, it might not benefit patients with extensive-stage SCLC under adequate follow-up with MRI surveillance. Finally, the heterogeneity of the included studies and publication bias were the main limitations of this study.
Keywords: brain metastases; prophylactic cranial irradiation; small cell lung cancer.