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

This study evaluated the efficacy and safety of thoracic radiotherapy (TRT) after first-line chemotherapy or chemoimmunotherapy in patients with extensive-stage small cell lung cancer (ES-SCLC), focusing on the impact of different TRT timing strategies (consolidative vs. salvage) on survival. A total of 54 ES-SCLC patients treated between January 2019 and July 2022 were retrospectively analyzed. Patients receiving consolidative TRT (cTRT) within 3 months after first-line treatment completion were compared to those receiving salvage TRT (sTRT) following disease progression. Primary endpoints included overall survival (OS), progression-free survival (PFS), locoregional-free survival (LRFS), and distant metastasis-free survival (DMFS); safety was a secondary endpoint. 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 identified cTRT as an independent favorable prognostic factor. No significant differences in OS or LRFS were found between high-dose (≥50 Gy) and low-dose (<50 Gy) TRT. Hematologic and respiratory toxicities were the most common adverse events, with acceptable tolerability. In conclusion, consolidative TRT after chemoimmunotherapy significantly improves survival outcomes in ES-SCLC patients, and low-dose TRT may be a suitable option.