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Purpose: Myxopapillary ependymoma (MPE) is a rare, typically slow-growing subtype of spinal ependymomas. There are no standard guidelines for radiotherapy and long-term outcomes after radiation, particularly patterns of relapse, for pediatric and young adult (YA) patients with MPE remain under-characterized., Methods and Materials: This is an Institutional Review Board-approved multi-institutional retrospective cohort study of 60 pediatric and YA patients diagnosed with MPE and received radiotherapy between 2000-2020. Clinical and treatment characteristics, and long-term outcomes were recorded. Site(s) of progression was compared to radiation fields. Survival outcomes were analyzed using Kaplan-Meier method. Cumulative incidence of local in-field progression (CILP) after initial radiotherapy was analyzed using Gray's method with out-of-field-only progression as a competing risk. Univariate analyses were performed using Cox proportional hazard's model., Results: The median age at radiation was 14.8 years (range: 7.1-26.5). At time of radiotherapy, 45 (75.0%) and 35 (58.3%) patients had gross residual and multifocal disease, respectively. Forty-eight (80.0%), seven (11.7%) and five (8.3%) patients received involved field radiotherapy, craniospinal irradiation, and whole spine radiation, respectively. Median follow-up from end of radiotherapy was 6.2 years (range: 0.6-21.0). Five-year overall survival, progression-free survival, and CILP were 100%, 60.8% and 4.1%, respectively. Both local recurrences were at sites of gross residual disease. Of the eighteen out-of-field first recurrences after radiotherapy, all were superior to the initial treatment field and nine had intracranial relapse. On univariate analyses, distant-only recurrence before radiation (HR: 4.00, 95% CI: 1.54-10.43, p = 0.005) was significantly associated with shorter time to progression., Conclusions: While the risk of recurrence within the radiation field is low, pediatric and YA patients with high-risk MPE remain at risk for recurrences in the spine above the radiation field and intracranially after radiotherapy. Future prospective studies are needed to investigate the appropriate radiation field and dose based on the extent of metastases., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Hippocampal avoidance (HA) has been shown to preserve cognitive function in adult patients with cancer treated with whole-brain radiation therapy for brain metastases. However, the feasibility of HA in pediatric patients with brain tumors has not been explored because of concerns of increased risk of relapse in the peri-hippocampal region. Our aim was to determine patterns of recurrence and incidence of peri-hippocampal relapse in pediatric patients with medulloblastoma (MB)., Methods and Materials: We identified pediatric patients with MB treated with protons between 2002 and 2016 and who had recurrent disease. To estimate the risk of peri-hippocampal recurrence, three hippocampal zones (HZs) were delineated corresponding to ≤5 mm (HZ-1), 6 to 10 mm (HZ-2), and >10 mm (HZ-3) distance of the recurrence from the contoured hippocampi. To determine the feasibility of HA, three standard-risk patients with MB were planned using either volumetric-modulated arc therapy (VMAT) or intensity-modulated proton therapy (IMPT) plans., Results: Thirty-eight patients developed a recurrence at a median of 1.6 years. Of the 25 patients who had magnetic resonance imaging of the recurrence, no patients failed within the hippocampus and only two patients failed within HZ-1. The crude incidence of peri-hippocampal failure was 8%. Both HA-VMAT and HA-IMPT plans were associated with significantly reduced mean dose to the hippocampi (p < .05). HA-VMAT and HA-IMPT plans were associated with decreased percentage of the third and lateral ventricles receiving the prescription craniospinal dose of 23.4 Gy., Conclusions: Peri-hippocampal failures are uncommon in pediatric patients with MB. Hippocampal avoidance should be evaluated in a prospective cohort of pediatric patients with MB., Plain Language Summary: In this study, the patterns of disease recurrence in patients with a pediatric brain tumor known as medulloblastoma treated with proton radiotherapy were examined. The majority of failures occur outside of an important structure related to memory formation called the hippocampus. Hippocampal sparing radiation plans using proton radiotherapy were generated and showed that dose to the hippocampus was able to be significantly reduced. The study provides the rationale to explore hippocampal sparing in pediatric medulloblastoma in a prospective clinical trial., (© 2022 The Authors. Cancer published by Wiley Periodicals LLC on behalf of American Cancer Society.)

Purpose: It is of great interest to physicians and patients/patients' families to be able to predict the amount of growth decrement after craniospinal irradiation (CSI). Little data exist on the effect of proton CSI. Our aim was to determine the effect of proton CSI on vertebral body (VB) growth retardation, and to identify factors associated with growth delay., Methods and Materials: We performed a retrospective outcome data analysis of 80 patients <16 years old with central nervous system tumors who received proton radiation therapy (PRT) at the Massachusetts General Hospital between 2002 and 2010 with available spinal magnetic resonance imaging. Forty-eight patients received CSI, and 32 patients with brain tumors who received focal cranial irradiation served as controls. VB height was measured midline using sagittal T1-weighted contrast or noncontrast enhanced magnetic resonance imaging of the spine. Measurements were repeated at multiple levels (C3, C3-C4, T4, T4-T5, C3-T6, T4-T7, L3, L1-L5) on available scans for the duration of follow-up. Data were fitted using a mixed-effects multivariable regression model, including follow-up time, CSI dose, age at CSI, and pretreatment VB percentile as parameters., Results: Median follow-up was 69.6 months for patients treated with proton CSI and 52.9 months for the control group. There was a significant association of CSI dose, follow-up time, age at treatment, and pretreatment VB percentile with VB growth retardation. Growth retardation was shown to be independent of gender or growth hormone deficiency., Conclusions: Although the current practice of PRT CSI delivery allows for sparing of the organs anterior to the spine, the vertebral column receives radiation therapy because of its close proximity to the targeted spinal canal. In growing children, the whole VB has generally been included so that growth impairment is even across the VB. We present a quantitative model predicting the growth retardation of patients treated with PRT CSI based on age at treatment, CSI dose, follow-up time, and pretreatment growth percentile., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Medulloblastoma (MB) is a rare central nervous system malignancy of adults, with limited contemporary studies to define treatment guidelines and expected late toxicity., Methods: A single-center, retrospective study was conducted of patients age ≥18 years from 1997-2019 with MB and who were treated with postoperative radiotherapy. Late toxicity was defined as a minimum of 18 months from diagnosis. Overall survival (OS) and progression-free survival (PFS) were characterized using Kaplan-Meier and Cox regression analyses., Results: Fifty-nine patients met criteria, with median age of 25 years (range 18-62 y) and median follow-up of 6.5 years (range 0.7-23.1 y). At diagnosis, 68% were standard-risk, 88% Chang M0, and 22% with anaplastic histology. Gross total resection was achieved in 75%; median craniospinal irradiation dose was 30.6 Gy (relative biological effectiveness [RBE]), median total dose was 54.0 Gy (RBE), 80% received proton radiotherapy; 81% received chemotherapy. 5 year PFS and OS were 86.5% and 95.8%, respectively; 10 year PFS and OS were 83.9% and 90.7%, respectively. Anaplastic histology was associated with worse PFS (P = .04). Among eight recurrences, 25% presented after 5 years. Most common grade ≥2 late toxicities were anxiety/depressive symptoms (30%), motor dysfunction (25%), and ototoxicity (22%). Higher posterior fossa radiation dose was associated with increased risk of late toxicity, including worse cognitive dysfunction (P = .05)., Conclusions: Adults with MB have favorable survival outcomes, but late failures and toxicity are not uncommon. Better understanding of prognostic factors, possibly from molecular subtyping, may help to define more personalized treatments for patients with high risk of recurrence and long-term treatment sequelae., (© The Author(s) 2022. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Survivors of pediatric medulloblastoma experience long-term morbidity associated with the toxic effects of postoperative radiotherapy (RT). Proton RT limits radiation dose to normal tissues thereby reducing side effects of treatment while maintaining high cure rates. However, long-term data on disease outcomes and long-term effects of proton RT remain limited., Methods: One hundred seventy-eight pediatric medulloblastoma patients treated with proton RT between 2002 and 2016 at the Massachusetts General Hospital comprise the cohort of patients who were treated with surgery, radiation therapy, and chemotherapy. We evaluated event-free survival (EFS), overall survival (OS), and local control using the Kaplan-Meier method. The cumulative incidence of brainstem injury and secondary malignancies was assessed., Results: Median follow-up was 9.3 years. One hundred fifty-nine patients (89.3%) underwent a gross total resection (GTR). The 10-year OS for the entire cohort, standard-risk (SR), and intermediate/high-risk (IR/HR) patients was 79.3%, 86.9%, and 68.9%, respectively. The 10-year EFS for the entire cohort, SR, and IR/HR cohorts was 73.8%, 79.5%, and 66.2%. The 10-year EFS and OS for patients with GTR/NTR were 75.3% and 81.0% vs 57.7% and 61.0% for subtotal resection (STR). On univariate analysis, IR/HR status was associated with inferior EFS, while both anaplastic histology and IR/HR status were associated with worse OS. The 10-year cumulative incidence of secondary tumors and brainstem injury was 5.6% and 2.1%, respectively., Conclusions: In this cohort study of pediatric medulloblastoma, proton RT was effective, and disease outcomes were comparable to historically treated photon cohorts. The incidence of secondary malignancies and brainstem injury was low in this cohort with mature follow-up., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Purpose: Few studies report outcomes in children treated with radiation for nonmyxopapillary ependymoma of the spinal cord, and little evidence exists to inform decisions regarding target volume and prescription dose. Moreover, virtually no mature outcome data exist on proton therapy for this tumor. We describe our combined institutional experience treating pediatric classical/anaplastic ependymoma of the spinal cord with proton therapy., Methods and Materials: Between 2008 and 2019, 14 pediatric patients with nonmetastatic nonmyxopapillary grade II (n = 6) and grade III (n = 8) spinal ependymoma received proton therapy. The median age at radiation was 14 years (range, 1.5-18 years). Five tumors arose within the cervical cord, 3 within the thoracic cord, and 6 within the lumbosacral cord. Before radiation therapy, 3 patients underwent subtotal resection, and 11 underwent gross-total or near total resection. Two patients received chemotherapy. For radiation, the clinical target volume received 50.4 Gy (n = 8), 52.2 (n = 1), or 54 Gy (n = 5), with the latter receiving a boost to the gross tumor volume after the initial 50.4 Gy, modified to respect spinal cord tolerance., Results: With a median follow-up of 6.3 years (range, 1.5-14.8 years), no tumors progressed. Although most patients experienced neurologic sequela after surgery, only 1 developed additional neurologic deficits after radiation: An 18-year-old male who received 54 Gy after gross total resection of a lumbosacral tumor developed grade 2 erectile dysfunction. There were 2 cases of musculoskeletal toxicity attributable to surgery and radiation. At analysis, no patient had developed cardiac, pulmonary, or other visceral organ complications or a second malignancy., Conclusion: Radiation to a total dose of 50 to 54 Gy can be safely delivered and plays a beneficial role in the multidisciplinary management of children with nonmyxopapillary spinal cord ependymoma. Proton therapy may reduce late radiation effects and is not associated with unexpected spinal cord toxicity., (Copyright © 2021 Elsevier Inc. All rights reserved.)