Purpose The purpose of this study was to analyze the patterns of failure and survival outcome in patients with brain metastases who received whole-brain radiotherapy (WBRT) with hippocampal avoidance (HA) using simultaneous integrated boost (SIB) on metastatic brain tumors. Materials and Methods We retrospectively reviewed 42 patients treated with HA-WBRT for brain metastases. A total of 25 Gy for whole brain and 35-55 Gy for gross tumors were delivered with 10 fractionations. Local tumor and intracranial progression were defined as a recurrence or tumor progression in SIB field and any recurrence or tumor progression within whole brain, respectively. Progression in HA zone was defined as the recurrence within the area expanded 5 mm from HA zone. Results Median follow-up duration was 10.0 months (range, 4.1 to 56.4 months). Intracranial progression was observed in 13 patients (31.0%) and the median duration from the start of HA-WBRT to progression was 10.6 months (range, 0.9 to 33.0 months). Local tumor progression and new metastasis outside SIB field occurred in 10 patients (23.8%) and nine patients (21.4%), respectively. There was no isolated hippocampal metastasis, except only one patient (2.4%) with multiple metastases inside and outside HA zone simultaneously. Median survival time and intracranial progression-free survival rate at 1 year were 19.4 months (95% confidence interval [CI], 9.6 to 29.2) and 71.5%, respectively, and those for overall survival were 26.5 months (95% CI, 15.4 to 37.5) and 67.9%, respectively. Conclusion HA-WBRT was associated with low risk of new metastasis in HA region in the patients with brain metastases. These findings would serve as useful guidance on applying HA-WBRT in clinical practice.

Purpose This multicenter retrospective study aimed to investigate prognostic factors for survival, encompassing clinical and radiologic features and treatments, in newly diagnosed diffuse intrinsic pontine glioma (DIPG) patients treated with radiotherapy. Methods Patients <30 years of age who underwent radiotherapy as an initial treatment for DIPG between 2000 and 2018 were included; patients who did not undergo an MRI at diagnosis and those with pathologically diagnosed grade I glioma were excluded. We examined medical records of 162 patients collected from 10 participating centers in Korea. The patients’ clinical and radiological variables, molecular and histopathologic data, and treatment response were evaluated to identify the prognosticators for DIPG and estimate survival outcomes. Results The median follow-up period was 10.8 months (interquartile range, 7.5–18.1). The 1- and 2-year overall survival (OS) rates were 53.5% and 19.0%, respectively, with a median OS of 13.1 months. Long term survival rate (≥2 years) was 16.7%, and median OS was 43.6 months. Age (<10 years), poor performance status, treatment before 2010, and post-radiotherapy necrosis were independent prognostic factors related to poor OS in the multivariate analysis. In patients with increased post-radiotherapy necrosis, the median OS was 13.3 months for bevacizumab group and 11.4 months for no-bevacizumab group (P = 0.138). Conclusion Therapeutic strategy for DIPG has remained unchanged over time, and its prognosis remains poor. Our findings suggest that appropriate efforts are needed to reduce the occurrence of post-radiotherapy necrosis. Further well-designed clinical trials are recommended to improve the poor prognosis observed in DIPG patients.