Background: The CREST trial established the benefit of consolidative thoracic radiotherapy (TRT) following first line (1L) chemotherapy in extensive-stage small cell lung cancer (ES-SCLC), demonstrating improved 2-year overall survival (OS). However, the role of TRT in the chemoimmunotherapy (CT-IO) era remains unclear, as TRT was excluded from registrational trials.
Methods: This retrospective study analysed consecutive patients (pts) with ES-SCLC treated with 1L CT-IO between January 2020 and January 2024 across 4 centres. Pts without radiological progression (PD) at their first post-treatment assessment were included. Intrathoracic recurrence rates, progression-free survival (PFS), and OS were compared between pts who received TRT and those who did not.
Results: 336 pts were identified, with 111 (33.0 %) receiving TRT. Pts who received TRT had a lower rate of intrathoracic PD compared to those who did not (40.5 % vs 57.8 %, p = 0.003). Among those with intrathoracic PD despite TRT, only 21 (24.1 %) experienced PD within the radiation field. With a median follow-up of 31.3 months, pts who received TRT showed improved PFS (HR 0.89, p = 0.363) and OS (HR 0.82, p = 0.142), although not statistically significant. Multivariate analysis identified baseline liver metastases (LM) and stable disease after CT-IO as independent predictors of shorter PFS. Subgroup analysis revealed a longer PFS for pts receiving higher TRT doses (≥45 Gy vs <45 Gy) and those without LM.
Conclusions: In this series, TRT following 1 L CT-IO significantly improved intrathoracic control, although it did not translate into significantly better survival outcomes. Prospective trials are warranted to evaluate the impact of TRT on quality of life and survival.
Keywords: Chemoimmunotherapy; Consolidation radiotherapy; Extensive-stage small-cell lung cancer; Thoracic radiotherapy.
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