The effect and toxicity profile of consolidative or salvage thoracic radiotherapy following chemoimmunotherapy in patients with extensive-stage small cell lung cancer

The present study assessed the efficacy and safety of thoracic radiotherapy (TRT) following first-line chemotherapy or chemoimmunotherapy in patients with extensive-stage small cell lung cancer (ES-SCLC), focusing on the influence of different TRT timing strategies (consolidative vs. salvage) on survival rates. We retrospectively analyzed a total of 54 ES-SCLC patients treated between January 2019 and July 2022. Patients receiving consolidative TRT (cTRT) within three months after first-line treatment completion were compared with those receiving salvage TRT (sTRT) following disease progression. The primary endpoints were overall survival (OS), progression-free survival (PFS), locoregional-free survival (LRFS), and distant metastasis-free survival (DMFS); the secondary endpoint included safety. The cTRT group (n = 41) showed significantly longer median OS (26.6 vs. 14.8 months, P = 0.048), PFS (12.9 vs. 3.5 months, P < 0.0001), and DMFS (10.7 vs. 3.4 months, P = 0.0044) than the sTRT group (n = 13). Multivariate analysis revealed cTRT as an independent favorable prognostic factor. No significant differences in OS or LRFS were observed between high-dose (≥ 50 Gy) and low-dose (< 50 Gy) TRT. Hematologic and respiratory toxicities were the most frequently reported adverse events, with acceptable tolerability. In conclusion, cTRT after chemoimmunotherapy significantly improves survival outcomes for ES-SCLC patients, and low-dose TRT may be a suitable option.