Efficacy and patient selection of consolidative thoracic radiotherapy following chemoimmunotherapy in ES-SCLC

Background Despite significant progress with immunotherapy in extensive-stage small-cell lung cancer (ES-SCLC), progression-free survival (PFS) remains limited, and relapse is common. Whether consolidative thoracic radiotherapy (cTRT) administered after first-line chemoimmunotherapy offers additional clinical benefit remains uncertain, and the lack of clear patient selection criteria further restricts its application in real-world. Methods ES-SCLC patients who received first-line PD-1/PD-L1 inhibitor plus platinum-etoposide and achieved disease control were included. All patients were divided into two groups based on whether they received cTRT. The primary endpoint was PFS. Secondary endpoints included overall survival (OS), depth of response (DpR), and safety. Results A total of 91 patients were included. DpR analysis showed a higher incidence of additional tumor shrinkage in the cTRT group ( P = 0.007). Patients who received cTRT had significantly longer unadjusted median PFS and median OS (log-rank test P < 0.001). After weighting, survival differences were attenuated but remained numerically in favor of the cTRT group. Cox analysis showed receipt of cTRT was independently associated with prolonged PFS ( P = 0.036) and OS ( P = 0.033). Logistic regression revealed that poorer ECOG PS ( P = 0.047) and higher clinical stage ( P = 0.046) were independently associated with a lower likelihood of receiving cTRT. Toxicities were manageable; radiation-related events were mostly grade 1–2, and no grade 5 adverse events occurred. Conclusion The cTRT following chemoimmunotherapy was associated with a higher incidence of additional tumor shrinkage and was independently related to longer survival. Prospective randomized trials are needed to identify the optimal efficacy and patient selection criteria for cTRT practice.