Real-world Clinical Outcomes in Patients with Limited Stage SCLC Who Received High-dose Hyperfractionated Simultaneous Integrated Boost Radiotherapy versus Standard-dose radiotherapy

Background: A phase 3 trial has shown that high-dose, accelerated, hyperfractionated, twice-daily thoracic radiotherapy (54 Gy in 30 fractions) is clinically effective for limited-stage small-cell lung cancer (LS-SCLC) patients under 70.This retrospective study compares the real-world effectiveness of high-dose hyperfractionated simultaneous integrated boost radiotherapy with standard-dose radiotherapy.Methods: This retrospective study was conducted at ****, including patients with histologically or cytologically confirmed LS-SCLC.All eligible patients received four courses of thoracic radiotherapy combined with concurrent chemotherapy (cisplatin or carboplatin and etoposide).Patients were categorized into three groups based on the radiotherapy dose: the 54 Gy group (54 Gy in 30 fractions, twice daily), the 45 Gy group (45 Gy in 30 fractions, twice daily), and the 60 Gy group (60-70 Gy in 30-35 fractions, once daily).The primary endpoints were real-world progression-free survival (rwPFS ) and overall survival (OS).Results: Between March 2010 and November 2024, a total of 353 patients were inclued in the study.The median follow-up was 54.9 months (range, 2.9 to 151.6).After applying inverse probability of treatment weighting (IPTW), the clinical features were well balanced between the groups.The median rwPFS was significantly better in the 54 Gy group (29.7 months [95% CI 15.9-NA]) compared to the 45 Gy group (15.0 months [95% CI 11.8-30.4];hazard ratio 1.23 [95% CI 1.01-1.50])and the 60 Gy group (13.5 months [95% CI 11.4-15.9];HR 1.29 [95% CI 1.09-1.54])both before (p=0.011)and after (p=0.033)IPTW.The median OS was also significantly longer in the 54 Gy group (63.9 months [95% CI 57.1-NA]) compared to the 45 Gy group (42.9 months [95% CI 32.3-70.8];HR 1.76 [95% CI 1.19-2.61])and the 60 Gy group (38.0 months [95% CI 30.8-51.9];HR 1.60 [95% CI 1.05-2.44])both before (p=0.015)and after (p=0.006)IPTW.Treatment-related toxicities were similar across the three groups. Conclusion:High-dose, accelerated, hyperfractionated, twice-daily thoracic radiotherapy (54 Gy) was well tolerated and effective in this large, real-world cohort study of patients with LS-SCLC