The effects and toxicity profiles of consolidative and 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 <i>vs.</i> salvage) on survival rates. We retrospectively analyzed a total of 54 patients with ES-SCLC treated between January 2019 and July 2022. Patients receiving consolidative TRT (cTRT) within three months after completion of first-line treatment were compared with those receiving salvage TRT (sTRT) after 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 ( <i>n</i> = 41) showed significantly longer median OS (26.6 <i>vs.</i> 14.8 months, <i>P</i> = 0.048), PFS (12.9 <i>vs.</i> 3.5 months, <i>P</i> < 0.0001), and DMFS (10.7 <i>vs.</i> 3.4 months, <i>P</i> = 0.0044) than the sTRT group ( <i>n</i> = 13). Multivariate analysis revealed that cTRT was 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.