Abstract
INTRODUCTION: Immune checkpoint inhibitor (ICI)-based treatment has become standard treatment for patients with advanced NSCLC. We aimed to determine the survival benefit of upfront radiotherapy for brain metastases (BMs) in patients with NSCLC who received ICI alone (ICI-alone) or with chemotherapy (ICI-chemo). METHODS: This study included consecutive patients with NSCLC having BMs who received ICI alone or ICI-chemo at 50 institutes between February 2017 and September 2021. The presence of BMs was confirmed by imaging before treatment. Treatment outcomes were compared between patients who did and did not receive upfront radiotherapy for BMs. Potential confounding factors were adjusted between the groups through inverse probability treatment weighting (IPTW) analysis and overlap weighting (OW) analysis with propensity scores. RESULTS: Patients were grouped as ICI-alone cohort, 224 patients (upfront-radiotherapy group, 135 patients; no-radiotherapy group, 89 patients) and ICI-chemo cohort, 367 patients (upfront-radiotherapy group, 212 patients; no-radiotherapy group, 155 patients). In the ICI-alone cohort, the overall survival of the upfront-radiotherapy group was significantly longer than that of the no-radiotherapy group (IPTW-adjusted hazards ratio [HR] = 0.45 [95% confidence interval [CI]: 0.29-0.72], OW-adjusted HR = 0.52 [95% CI: 0.35-0.77]). In contrast, in the ICI-chemo cohort, the OS of the upfront-radiotherapy group was not significantly different from that of the no-radiotherapy group (IPTW-adjusted HR = 1.02 [95% CI: 0.70-1.48], OW-adjusted HR = 0.93 [95% CI: 0.65-1.33]). CONCLUSIONS: Upfront radiotherapy for BMs was associated with longer overall survival in patients with NSCLC who received ICI alone; however, it did not exhibit survival benefits in the patients who received ICI-chemo.