2641 - Whole-Brain Radiation Therapy with Simultaneous Integrated Boost vs. Stereotactic Radiotherapy for the Treatment of Brain Metastasis from Non-Small Cell Lung Cancer

Z. Wu¹, Y. Chen¹, L. Lu², S. H. Zheng¹, and M. Chen³; ¹State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060, P. R. China., Guangzhou, China, ²Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China, ³Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Sun Yat-sen University, Guangzhou, Guangdong, China

Purpose/Objective(s): To compare whole-brain radiotherapy with a simultaneous integrated boost (WBRT-SIB) to stereotactic radiotherapy (SRT) in treating non-small cell lung cancer (NSCLC) patients with brain metastases (BMs) and investigate the prognostic factors of intracranial progression-free survival (iPFS) and overall survival (OS). Materials/

Methods: Between July 2012 and March 2023, NSCLC patients receiving WBRT-SIB or SRT for 1-10 BMs were reviewed. A 1:1 propensity score matching was conducted to generate two groups with similar known baseline characteristics. iPFS, OS, the cumulative incidence of local tumor progression, and intracranial distant tumor progression were compared between groups.
Results: A cohort of 379 patients was included in this study. After propensity score matching, there were 83 patients in the WBRT-SIB and the SRT groups, respectively. The WBRT-SIB group had a significantly longer median iPFS than the SRT group (8.3 months vs. 6.0 months, P = 0.046). The median OS (P = 0.107) and the cumulative incidence of local tumor progression (P = 0.063) were similar between the two groups. WBRT-SIB was associated with reduced intracranial distant tumor progression (P = 0.015). No toxicities higher than grade 3 were observed in both groups. The absence of extracranial metastases was an independent prognostic factor of OS (hazard ratio, 0.472; 95% CI, 0.278-0.802; P = 0.006 [Model 1]; hazard ratio, 0.444; 95% CI, 0.260-0.759; P = 0.003 [Model 2]). Multivariable analysis showed that assignment to WBRT-SIB (HR, 0.663 [95% CI, 0.441-0.998]; P = 0.049), male (HR, 0.630 [95% CI, 0.401-0.990]; P = 0.045), and positive epidermal growth factor receptor (EGFR) or anaplastic lymphoma kinase (ALK) gene mutation (HR, 0.542 [95% CI, 0.344-0.855]; P = 0.008) were associated with better iPFS.
Conclusion: Compared to SRT, the iPFS of NSCLC patients with BMs was prolonged after WBRT-SIB, mainly related to better control of distant intracranial tumors. WBRT-SIB can be a safe alternative option for patients with BMs. We also found that the absence of extracranial metastases was associated with better OS and patients with EGFR or ALK mutation and male ones appeared to have a longer iPFS.