1105 - SFRT vs. CRT/SBRT: A Clinical Trials Simulated (CTS) Study on Short-Term Objective Response Rate, Long-Term Local Control Rate and Efficacy Gain Prediction for Bulky Tumors
Presenter(s)
S. Bi1, S. Pan2, X. Huang3, and Z. Dai4; 1Post-Doctoral Research Center, Yuebei People's Hospital, Southern Medical University, Shaoguan, Guangdong Province, China, Shaoguan, China, 2Department of radiotherapy, Yuebei people’s Hospital, Shantou University Medical College, Shantou, Guangdong Province, China., Shaoguan, China, 3Department of Medical Image Center, Yuebei People's Hospital, Guangdong Province, China, 512026., Shaoguan, China, 4National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital,Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, ShenZhen, Guangdong, China
Purpose/Objective(s): Spatial Fractionated Radiation Therapy (SFRT), has emerged as a promising approach for bulky tumors and lesions adjacent to critical organs. However, existing evidence remains fragmented, with limited long-term efficacy data and a lack of head-to-head comparisons with conventional fractionated radiotherapy (CRT) and Stereotactic Body Radiation Therapy (SBRT). This clinical trial simulation (CTS) integrated meta-analysis, Linear-Quadratic (LQ) model, and Weibull survival model to systematically evaluate SFRT’s efficacy, safety, and clinical utility, addressing core evidence gaps.
Materials/Methods: A three-tier analytical framework was established: 1) Core comparison (SFRT vs CRT) using direct meta-analysis of 21 eligible studies (3 direct comparisons + 18 single-arm studies with matched historical controls); 2) Secondary comparison (SFRT vs SBRT) via indirect network meta-analysis with CRT as the common comparator; 3) Subgroup analysis exploring heterogeneity by SFRT technique (GRID vs LRT vs proton SFGRT) and tumor location (bone metastases vs visceral metastases vs primary tumors). Mathematical modeling (Linear-Quadratic [LQ] model for biologically effective dose [BED]-local control rate [LCR] correlation; Weibull model for long-term overall survival [OS] extrapolation) was employed to fill data gaps. Sensitivity analyses (exclusion of low-quality studies, model parameter adjustment) validated result robustness.
Results: SFRT demonstrated significantly superior 12-month LCR compared to CRT (pooled RR=1.32, 95% CI:1.15-1.52, P=0.0002) with substantially lower Grade 3+ toxicity (pooled RR=0.52, 95% CI:0.38-0.71, P<0.0001). No significant difference in 2-year OS was observed (pooled HR=1.03, 95% CI:0.89-1.19, P=0.68). Indirect comparison revealed SBRT’s advantage in long-term OS (HR=2.94, 95% CI:2.07-4.18, P<0.0001), but SFRT showed superior normal tissue sparing in bulky tumors (>5cm) and OAR-adjacent lesions. LQ modeling indicated a strong positive correlation between BED and 3-year LCR (R²=0.99), with SFRT achieving 76.3% 3-year LCR at BED=72Gy. Weibull extrapolation confirmed SFRT’s survival benefit in advanced tumors (5-year OS=0.5% vs CRT=0.3% for NSCLC metastases). Subgroup analysis identified bone metastases and visceral metastases as the most favorable indications for SFRT.
Conclusion: SFRT offers a favorable efficacy-to-toxicity balance for bulky tumors and lesions adjacent to critical organs, complementing CRT and SBRT in clinical practice. The CTS (meta-analysis + mathematical modeling) provides robust evidence to guide clinical decision-making, with bone and visceral metastases as priority indications for SFRT implementation.