Consolidation thoracic radiotherapy after chemoimmunotherapy provides survival benefit in elderly patients with extensive-stage small-cell lung cancer: a multicenter study

Background: Previous studies have demonstrated that thoracic radiotherapy (TRT) following first-line chemoimmunotherapy improves survival in extensive-stage small cell lung cancer (ES-SCLC). However, its efficacy and safety in elderly patients remain unclear. Objectives: To evaluate the efficacy and safety of consolidative TRT in elderly patients with ES-SCLC following first-line chemoimmunotherapy. Design: A multicenter retrospective cohort study. Methods: Elderly (⩾70 years old) ES-SCLC patients from three large-scale cancer centers who received chemoimmunotherapy in the first line were included, they were divided into two groups according to whether they received TRT. The primary outcomes were overall survival (OS) and progression-free survival (PFS). Results: A total of 240 patients who completed four to six of first-line chemoimmunotherapy without progression were included, 83 of whom received consolidative TRT. In the analysis with time zero set at chemoimmunotherapy initiation, TRT was associated with longer median PFS (10.56 vs 8.30 months; hazard ratio (HR), 0.71, p = 0.034) and median OS (18.43 vs 14.39 months; HR, 0.64, p = 0.008). Using time-dependent Cox models with time zero reset to cycle 4 completion to address guarantee-time bias, TRT remained significantly associated with improved OS (14.59 vs 10.92 months; HR, 0.64, p = 0.007) and PFS (7.80 vs 5.12 months; HR, 0.72, p = 0.047). The presence of baseline liver metastasis emerged as an independent adverse prognostic factor. No significant increase in grade ⩾3 adverse events was observed in patients receiving TRT. Conclusion: In elderly ES-SCLC patients undergoing first-line chemoimmunotherapy, the addition of TRT is associated with a survival benefit and an acceptable safety profile. These results hold significant implications for current clinical practice and may help inform treatment strategies for elderly patients with ES-SCLC.