Patterns of failure in pediatric medulloblastoma and implications for hippocampal sparing.

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.

Quantifying the climate benefits of a virtual versus an in-person format for an international conference.

BACKGROUND: Academic institutions across the globe routinely sponsor large conferences. During the COVID-19 pandemic, many conferences have used all- or partially virtual formats. The conversion of the 2021 Consortium of Universities for Global Health (CUGH) conference, originally planned in-person for Houston, TX USA to an all-virtual format provided an opportunity to quantify the climate-related impacts of in-person versus virtual conferences. METHODS: From the 2021 CUGH conference registration data, we determined each registrant's distance from Houston. Using widely available, open-source formulas, we calculated the carbon footprint of each registrant's round-trip drive or flight had they traveled to Houston. We assumed that registrants traveling more than 300 miles would have flown, with the remainder traveling by automobile. RESULTS: Of 1909 registrants, 1447 would have traveled less than 4000 miles, and 389 would have traveled more than 10,000 miles round trip. Total travel-related carbon emissions were estimated at 2436 metric tons of CO2, equivalent to the conservation of 2994 acres of forest for a year. CONCLUSIONS: Organizations can now readily quantify the climate cost of annual conferences. CUGH's annual international conference, when held in-person, contributes significantly to carbon emissions. With its focus on promoting global health equity, CUGH may play a lead role in understanding the pros and cons for planetary health of in-person versus virtual conferences. CUGH and other organizations could routinely measure and publish the climate costs of their annual conferences.

Decade-long disease, secondary malignancy, and brainstem injury outcomes in pediatric and young adult medulloblastoma patients treated with proton radiotherapy.

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.