Consolidative thoracic radiotherapy in the immunotherapy era for extensive-stage small cell lung cancer: a systematic review and meta-analysis with emphasis on brain and liver metastases.

Abstract

Immunotherapy has redefined the therapeutic paradigm in extensive-stage small cell lung cancer (ES-SCLC). However, the potential role of consolidative thoracic radiotherapy (cTRT) in this context remains unresolved. This study evaluated the efficacy and safety of cTRT in patients with ES-SCLC treated with chemoimmunotherapy, with particular focus on patients with baseline liver and brain metastasis. A systematic review and pairwise meta-analysis were conducted per PRISMA guidelines, including studies from PubMed, Embase, and Scopus up to September 1, 2025. Outcomes were reported as hazard ratios (HR) for overall survival (OS), progression-free survival (PFS), and brain metastasis-free survival (BMFS), and odds ratios (OR) for treatment-related adverse events (TRAEs) with 95 % confidence intervals (95 % CI). Twenty studies involving 5282 patients were included. cTRT combined with chemoimmunotherapy improved OS (HR: 0.57, 95 %CI: 0.48-0.66, p < 0.001) and PFS (HR: 0.53, 95 %CI: 0.45-0.63, p < 0.001). In patients with baseline brain metastasis, cTRT improved both OS (HR:0.57, 95 %CI: 0.39-0.84, p = 0.01) and PFS (HR:0.42, 95 %CI: 0.28-0.64, p < 0.001), whereas in patients with liver metastasis, there was no improvement. Furthermore, cTRT increased BMFS (HR: 0.46, 95 %CI: 0.33-0.64, p < 0.001). Grade ≥ 3 pneumonitis and esophagitis were observed in 3.86 % and 1.27 % of cTRT patients, respectively. cTRT confers significant improvements in OS and PFS in the general population of patients with ES-SCLC, as well as in patients with baseline brain metastasis. Moreover, cTRT may be associated with prolonged BMFS, potentially reflecting an abscopal effect. The safety profile remains acceptable, given the substantial survival benefit.