Influence of prophylactic cranial irradiation (PCI) in the first-line treatment of limited-stage small cell lung cancer (LS-SCLC)

Abstract

The survival benefit of prophylactic cranial irradiation (PCI) in limited-stage small cell lung cancer (LS-SCLC) is generally based on data that do not reflect the modern era in which magnetic resonance imaging (MRI) is actively used. In this study, we aimed to investigate the cumulative incidence of brain metastasis between patient groups treated with and without PCI in a cohort where MRI was routinely used for staging and follow-up. METHODS A total of 73 patients with LS-SCLC who achieved a response to concurrent chemoradiotherapy (cCRT) at our institution between March 2010 and December 2023 were retrospectively analyzed. Radiotherapy was usually administered with dose escalation using a twice-daily schedule (54 Gy in 30 fractions). Patients were divided into two groups according to PCI administration. RESULTS Among 73 patients (38 PCI, 35 non-PCI), baseline characteristics were similar between groups. The use of first-line immunotherapy and dose-escalated twice-daily radiotherapy were significantly higher in the non-PCI group. The cumulative incidence of central nervous system (CNS) recurrence in the entire cohort was 26%, and it was similar between PCI and non-PCI groups (26.4% vs. 25.7%, p=0.953). However, the time to CNS recurrence was significantly longer in patients who received PCI (28 vs. 7 months, p=0.013). CONCLUSION Our study indicates that PCI does not significantly reduce the cumulative incidence of metastasis in patients with LS-SCLC but prolongs the time to metastasis.