Efficacy of Whole-Brain Radiotherapy Plus Simultaneous Integrated Boost (SIB-WBRT) for brain metastases

Abstract

Objective: To investigate the outcomes of SIB-WBRT in patients with brain metastases and analyze the impact of some factors on prognosis. Methods: This single-arm retrospective study analyzed patients with brain metastases treated with received SIB-WBRT (40 Gy/20 doses of whole brain tissue and tumor tissue pushed to 56-60 Gy/20 doses) at Peking Union Medical College Hospital from September 2015 to December 2021. The primary endpoint was intracranial progression free survival (iPFS). Secondary endpoints included overall survival (OS), intracranial new foci, and tumor control. The Kaplan-Meier method was then used to depict and estimate iPFS, OS, intracranial new incidence, and tumor control. Finally, the Cox model was used to analyze the association between some relevant factors and outcomes. Results: A total of 107 patients were included and the median iPFS in these patients treated with SIB-WBRT was 13.4 (95% CI: 4.2-22.6) months, with 66.3% (95% CI: 56.0%-77.0%) and 48.5% (95% CI: 36.0%-61.0%) iPFS at 6- and 12-months. The median local control was 37.6 (95% CI: 28.3-46.8) months, with local control rates of 83.9% (95% CI: 80.0%-88.0%) and 72.6% (95% CI: 67.0%-78.0%) at 6- and 12-months. The median time to appearance of new intracranial foci was 17.4 (95% CI: 17.1-20.8) months, and the 6- and 12-month control rates were 72.6% (95% CI: 62.0%-83.0%) and 58.8% (95% CI: 46.0%-72.0%). The number of brain metastases in patients before treatment was significantly associated with iPFS (HR=0.4, 95% CI: 0.1-0.9, P=0.0430). Conclusions: The iPFS, local control, and intracranial new foci of patients with brain metastases after treatment with SIB-WBRT were acceptable. In addition, the number of brain metastases in patients before treatment may be associated with iPFS.