Lack of Prophylactic Cranial Irradiation for Extensive Small-Cell Lung Cancer in Real Life, with the Emergence of Immunotherapy

Background: Prophylactic cranial irradiation (PCI) is recommended to decrease the in-cidence of brain metastases (BM) in extensive-stage small-cell lung cancer (ESSCLC) without BMafter response to chemotherapy. However, PCI is associated with significant neurocognitive effects,and new studies are debating its benefits. Moreover, the introduction of immunotherapy in themanagement of the disease has raised new questions, and there is a lack of data on PCI and im-munotherapy. We report a single-center retrospective study evaluating the impact of omitting PCIfrom real-life treatment, including immunotherapy, of patients with ES-SCLC. Methods: We identifiedpatients followed at APHM between January 2014 and January 2021 for ES-SCLC without BM withan indication for PCI. The main assessment criteria considered in this study were overall survival(OS) and brain metastasis-free survival (BMFS) between patients who received PCI and those whodid not. Results: 56 patients were included, 25 receiving PCI and 31 without PCI. The median follow-up was 16 months. Eighteen patients received immunotherapy, mostly in the group without PCI(p = 0.024). The median OS and BMFS were, respectively, 11.7 and 13.4 months in patients withPCI, and 20.3 and 10.7 months in patients without PCI, without any significant statistical difference(p = 0.412, p = 0.336). The prognostic factors highlighted in multivariate analysis were initial per-formance status (PS) < 2 for OS (HR = 2.74 (IC95% [1.23; 6.13])) and monocyte lymphocyte ratio(MLR) < 0.12 for BMFS (HR = 1.21 (IC95% [1.01; 1.45])). A recursive partitioning analysis (RPA) foundPS, immunotherapy, and age to be influential factors for OS but not PCI. Conclusions: The clinicalresults of our study showed no benefit of PCI in terms of OS and BMFS for patients with ES-SCLC.This can be explained by the lack of benefit of PCI or by the introduction of immunotherapy.