was 55, respectively. TRT was performed using 3-dimensional conformal radiation therapy (3DCRT) and delivered using 2Gy single fraction per day in 73.2% of patients. The median dose TRT was 50 Gy (45-65), and all patients received concurrent chemoradiotherapy. PCI was combined in 56 (55.4%) patients. Result: The median survival for all patients was 26.9 months. Local failure occurred in 41 patients (40.5%), and distant metastasis was noted in 54 patients (53.4%). The 3-year local control, progression-free survival (PFS), and overall survival (OS) rates were 52.0%, 29.5%, and 56.4%, respectively. On univariate analysis, the American Joint Committee on Cancer stage (p<0.001), timing of TRT (2 vs, >2 cycles, p¼0.017), tumor response (CR vs. PR, p¼0.015), the duration from the start date of chemotherapy to the end of TRT (SER) (70 vs >70 days, p¼0.025), and PCI (p¼0.003) were the significant predictors of OS and stage (p<0.001) and PCI (p¼0.017) were the significant predictors in PFS. Multivariate analysis revealed that stage (hazard ratio [HR], 3.61; 95% CI, 2.15-6.07) was the only significant factor in PFS and stage (HR, 2.49; 95% CI, 1.56-3.98), SER (HR, 1.93; 95% CI, 1.22-3.07), PCI (HR, 0.52; 95% CI, 0.33-0.84), and tumor response (HR, 1.76; 95% CI, 1.12 e 2.77) were the significant predictors in OS. There was one fatal radiation pneumonitis. Grade 3 radiation pneumonitis and esophagitis was shown in 7 (6.9%) vs. 7 (6.9%) patients, respectively. Grade 3 and 4 leukopenia was shown in 30 (29.7%) vs. 11 (10.8%) patients and febrile neutropenia was 9 (8.9%) vs. 1 (0.9%) patients, respectively. Conclusion: SER less than 70 days was a significant predictor of OS in LS-SCLC patients who received more than 45 Gy of TRT concurrently with chemotherapy. We could not find any significant positive survival benefits of TRT dose or BED escalation in our patients groups.
