Utility of Prophylactic Cranial Irradiation for Limited Stage Small Cell Lung Cancer in the Modern Era with Magnetic Resonance Imaging Surveillance

Abstract

AimsTo retrospectively analyse the impact of prophylactic cranial irradiation (PCI) on survival and intracranial progression in patients with limited stage small cell lung cancer (LS-SCLC) in the modern era of widespread magnetic resonance imaging brain screening. Materials and methodsPatients with LS-SCLC treated within our network between 2009 and 2020 who responded to initial therapy were stratified by receipt of PCI and stage of disease. A propensity score match analysis was carried out for stage II–III patients. Overall and neurological survival were defined as time to death and presumed death due to uncontrolled intracranial disease, respectively. Brain metastasis-free survival and symptomatic brain metastasis-free survival were defined as freedom from intracranial progression and symptomatic intracranial progression, respectively. The effect of PCI on these outcomes was assessed using Kaplan–Meier and Cox proportional hazards models. ResultsIn total, 243 (69.6%) of 349 patients received PCI. On multivariate analysis in the propensity matched stage II–III cohort, PCI was a significant predictor of improved neurological survival (hazard ratio 0.23, 95% confidence interval 0.08–0.65; P = 0.01), brain metastasis-free survival (hazard ratio 0.25, 95% confidence interval 0.12–0.51; P < 0.01) and symptomatic brain metastasis-free survival (hazard ratio 0.21, 95% confidence interval 0.08–0.55; P < 0.01), but not improved overall survival. Two-year neurological survival estimates within the propensity matched cohort were 96.8% (95% confidence interval 87.6–99.2%) with PCI and 77.2% (95% confidence interval 63.0–86.4%) without PCI and 1- and 2-year estimates of incidence of brain metastases were 3.9% (95% confidence interval 1.3–11.7%) and 11.7% (95% confidence interval 5.6–23.5%) in the PCI group and 31.6% (95% confidence interval 22.1–43.9%) and 40.4% (95% confidence interval 29.2–54.0%) in the no PCI group, respectively. ConclusionsIn the modern era of magnetic resonance imaging screening, PCI was associated with reduced incidence of intracranial progression in patients with stage II–III LS-SCLC who respond to initial therapy. This, importantly, translated to a decreased risk of neurological death within our propensity matched cohort, without significant improvement in overall survival.