Simultaneous Integrated Dose Reduction Radiotherapy Versus Conventional Fractionated Radiotherapy With Chemotherapy for Limited-Stage Small-Cell Lung Cancer in the Modern Treatment Era: a Phase III, Randomized Clinical Trial (SDR-RT trial)
Mené sur 336 patients atteints d'un cancer du poumon à petites cellules de stade limité (durée médiane de suivi : 56 mois), cet essai randomisé de phase III évalue l'efficacité, du point de vue de la survie sans progression, d'une radiothérapie avec réduction des volumes cibles par rapport à une radiothérapie avec fractionnement conventionnel
Background : Simultaneous integrated dose reduction (SDR) radiotherapy (SDR-RT) with a definitive dose to the gross tumor volume (GTV) and a relatively lower dose to the clinical target volume (CTV) might be beneficial in improving normal tissue sparing with low toxicity. This randomized controlled trial (SDR-RT trial) compared the efficacies of SDR-RT and conventional fractionated radiotherapy (CF-RT) for limited-stage small-cell lung cancer (LS-SCLC).
Methods: Eligible patients with LS-SCLC were 1 1 randomized to receive CF-RT (60 Gy in 30 once-daily fractions over 6 weeks for both CTV and GTV) or SDR-RT (50 Gy for CTV and 60 Gy for GTV in 28 once-daily fractions over 5.5 weeks) along with 4-6 cycles of chemotherapy. The primary endpoint was progression-free survival (PFS) rate in the intention-to-treat (ITT) population, whereas the secondary endpoints were overall survival (OS) rate and adverse event incidence.
Results : Between February 2017 and March 2023, 336 patients randomly received either SDR-RT (n = 165) or CF-RT (n = 171). Over a median follow-up of 56 months, the 2- and 5-year PFS rates in the ITT analysis were respectively 42.0% and 31.9% with SDR-RT, and 40.7% and 30.5% with CF-RT (P = 0.015 for noninferiority). The between-group differences in OS, locoregional PFS, and locoregional recurrence rates were nonsignificant. Compared with CF-RT, SDR-RT was associated with lower median values of V20 (21.0% vs. 22.8%) and Dmean (12.1 vs. 13.4 Gy) of the bilateral lungs (both P < 0.001). Acute grade ≥3 toxicities and radiation pneumonitis incidence were lower with SDR-RT than that with CF-RT (54.5% vs. 66.9%, P = 0.020; 2.4% vs. 7.7%, P = 0.027).
Conclusion : Compared with CF-RT, SDR-RT led to similar survival and less acute adverse events. SDR-RT may be considered as a more protective approach for LS-SCLC treatment. Trial registration : ClinicalTrials.gov, NCT04500145.
International Journal of Radiation Oncology, Biology, Physics , résumé, 2025