Comparing the effects of irradiation with protons or photons on neonatal mouse brain: Apoptosis, oncogenesis and hippocampal alterations.

BACKGROUND AND PURPOSE: Medulloblastoma (MB) is a common primary brain cancer in children. Proton therapy in pediatric MB is intensively studied and widely adopted. Compared to photon, proton radiations offer potential for reduced toxicity due to the characteristic Bragg Peak at the end of their path in tissue. The aim of this study was to compare the effects of irradiation with the same dose of protons or photons in Patched1 heterozygous knockout mice, a murine model predisposed to cancer and non-cancer radiogenic pathologies, including MB and lens opacity. MATERIALS AND METHODS: TOP-IMPLART is a pulsed linear proton accelerator for proton therapy applications. We compared the long-term health effects of 3 Gy of protons or photons in neonatal mice exposed at postnatal day 2, during a peculiarly susceptible developmental phase of the cerebellum, lens, and hippocampus, to genotoxic stress. RESULTS: Experimental testing of the 5 mm Spread-Out Bragg Peak (SOBP) proton beam, through evaluation of apoptotic response, confirmed that both cerebellum and hippocampus were within the SOBP irradiation field. While no differences in MB induction were observed after irradiation with protons or photons, lens opacity examination confirmed sparing of the lens after proton exposure. Marked differences in expression of neurogenesis-related genes and in neuroinflammation, but not in hippocampal neurogenesis, were observed after irradiation of wild-type mice with both radiation types. CONCLUSION: In-vivo experiments with radiosensitive mouse models improve our mechanistic understanding of the dependence of brain damage on radiation quality, thus having important implications in translational research.

Late-onset lymphopenia during radiation is associated with an increased risk of tumor recurrence in newly diagnosed pediatric medulloblastoma.

BACKGROUND: Recent data found a correlation between lymphopenia occurring early during craniospinal radiation therapy (RT) and risk of disease recurrence in newly diagnosed childhood medulloblastoma. However, the population included patients who received chemotherapy prior to or during RT. Here, we investigate the effect of lymphopenia during RT in patients with newly diagnosed pediatric medulloblastoma who were chemotherapy-naïve. PROCEDURE: We analyzed 79 patients with newly diagnosed medulloblastoma (ages 2-21 years) treated between 1997 and 2013 with craniospinal RT. Log-rank tests were used to determine survival differences, and Cox proportional hazards regression was used to assess associations between patient characteristics and lymphopenia with disease recurrence risk. RESULTS: Eighty-three percent of patients (62/75) had grade ≥3 lymphopenia by RT Week 3, with 95% developing grade ≥3 lymphopenia at some point during therapy. There was no difference in incidence of lymphopenia between those who received proton beam RT (93%) versus photon (97%). Twenty-four of 79 (30%) patients developed disease recurrence at an average 27.0 months after diagnosis. There was higher risk of disease recurrence in patients with grade ≥3 lymphopenia during RT Week 4 (log-rank p = .016; Cox p = .03) and Week 5 (log-rank p = .024; Cox p = .032); after adjusting for clinical risk group, only grade ≥3 lymphopenia at Week 4 remained prognostic (Cox p = .04). No correlation was found between risk of tumor recurrence and early lymphopenia (RT Weeks 0-3) or absolute lymphocyte count (ALC) below the median at any time during RT. CONCLUSIONS: Lymphopenia during RT Weeks 4 and 5 correlates with increased risk of tumor recurrence in pediatric patients with newly diagnosed medulloblastoma.

The pivotal role of irradiation-induced apoptosis in the pathogenesis and therapy of medulloblastoma.

BACKGROUND: Medulloblastoma (MB) is a rare primitive neuroectodermal tumors originating from the cerebellum. MB is the most common malignant primary brain tumor of childhood. MB originates from neural precursor cells in distinctive regions of the rhombic lip, and their maturation occurs in the cerebellum or the brain stem during embryonal development. Also, apoptosis is a programmed cell death associated with numerous physiological as well as pathological regulations. RECENT FINDINGS: Irradiation (IR)-induce apoptosis triggers cell death, with or without intervening mitosis within a few hours of IR and these share different morphologic alteration such as, loss of normal nuclear structure as well as degradation of DNA. Moreover, MB is strikingly sensitive to DNA-damaging therapies and the role of apoptosis a key treatment modality. Furthermore, in MB, the apoptotic pathways are made up of several triggers, modulators, as well as effectors. Notably, IR-induced apoptotic mechanisms in MB therapy are very complex and they either induce radiosensitivity or inhibit radioresistance leading to potential effective treatment strategies for MB. CONCLUSION: This review explicitly explores the pivotal roles of IR-induced apoptosis in the pathogenesis and therapy of MB.

Adaptive, behavioral, and emotional outcomes following postoperative pediatric cerebellar mutism syndrome in survivors treated for medulloblastoma.

OBJECTIVE: Patients who experience postoperative pediatric cerebellar mutism syndrome (CMS) during treatment for medulloblastoma have long-term deficits in neurocognitive functioning; however, the consequences on functional or adaptive outcomes are unknown. The purpose of the present study was to compare adaptive, behavioral, and emotional functioning between survivors with and those without a history of CMS. METHODS: The authors examined outcomes in 45 survivors (15 with CMS and 30 without CMS). Comprehensive neuropsychological evaluations, which included parent-report measures of adaptive, behavioral, and emotional functioning, were completed at a median of 2.90 years following craniospinal irradiation. RESULTS: Adaptive functioning was significantly worse in the CMS group for practical and general adaptive skills compared with the group without CMS. Rates of impairment in practical, conceptual, and general adaptive skills in the CMS group exceeded expected rates in the general population. Despite having lower overall intellectual functioning, working memory, and processing speed, IQ and related cognitive processes were uncorrelated with adaptive outcomes in the CMS group. No significant group differences or increased rates of impairment were observed for behavioral and emotional outcomes. CONCLUSIONS: Survivors with CMS, compared with those without CMS, are rated as having significant deficits in overall or general adaptive functioning, with specific weakness in practical skills several years posttreatment. Findings from this study demonstrate the high risk for ongoing functional deficits despite acute recovery from symptoms of CMS, highlighting the need for intervention to mitigate such risk.

Postradiation platinum-etoposide in adult medulloblastomas: retrospective analysis of hematological toxicity.

Aim: Adult medulloblastomas (MB) are rare, and optimal post-craniospinal irradiation (CSI) chemotherapy is not yet defined. We investigated hematological toxicity in patients treated with platinum-etoposide (EP) post-CSI. Methods: Retrospective, single-institution study to determine hematological toxicity in adult MB patients treated with EP (1995-2022). Results: Thirteen patients with a median follow-up of 50 months (range, 10-233) were analyzed. Four discontinued treatment due to toxicity, one after 1, 3 after 3 cycles. Hematological toxicities included grade 3 (5 patients) and grade 4 (6 patients). Two patients experienced post-treatment progression and died 16 and 37 months from diagnosis. Conclusion: Post-CSI EP demonstrates acceptable hematological toxicity in adult MB. However, the small cohort precludes definitive survival outcome conclusions. Prospective studies for comprehensive comparisons with other regimens are needed in this context.

Our study aimed to understand the effect of a chemotherapy combination (platinum and etoposide) on blood counts in adult patients with medulloblastoma after craniospinal radiation. Medulloblastoma is a rare brain cancer in adults. We analyzed data from 13 adult patients with medulloblastoma. The results show that the treatment leads to significant blood count-related side effects. Four of the patients discontinued their treatment early. Blood counts improved again after completion of treatment. Two patients had the tumor grow back after treatment and died later. Overall, the effect from this chemotherapy combination on blood counts was felt to be acceptable. The number of patients in this study was small, and more research is needed to determine the overall effectiveness of this treatment.

FANCD2 deficiency sensitizes SHH medulloblastoma to radiotherapy via ferroptosis.

Radiotherapy is one of the standard therapeutic regimens for medulloblastoma (MB). Tumor cells utilize DNA damage repair (DDR) mechanisms to survive and develop resistance during radiotherapy. It has been found that targeting DDR sensitizes tumor cells to radiotherapy in several types of cancer, but whether and how DDR pathways are involved in the MB radiotherapy response remain to be determined. Single-cell RNA sequencing was carried out on 38 MB tissues, followed by expression enrichment assays. Fanconi anemia group D2 gene (FANCD2) expression was evaluated in MB samples and public MB databases. The function of FANCD2 in MB cells was examined using cell counting assays (CCK-8), clone formation, lactate dehydrogenase activity, and in mouse orthotopic models. The FANCD2-related signaling pathway was investigated using assays of peroxidation, a malondialdehyde assay, a reduced glutathione assay, and using FerroOrange to assess intracellular iron ions (Fe2+ ). Here, we report that FANCD2 was highly expressed in the malignant sonic hedgehog (SHH) MB subtype (SHH-MB). FANCD2 played an oncogenic role and predicted worse prognosis in SHH-MB patients. Moreover, FANCD2 knockdown markedly suppressed viability, mobility, and growth of SHH-MB cells and sensitized SHH-MB cells to irradiation. Mechanistically, FANCD2 deficiency led to an accumulation of Fe2+ due to increased divalent metal transporter 1 expression and impaired glutathione peroxidase 4 activity, which further activated ferroptosis and reduced proliferation of SHH-MB cells. Using an orthotopic mouse model, we observed that radiotherapy combined with silencing FANCD2 significantly inhibited the growth of SHH-MB cell-derived tumors in vivo. Our study revealed FANCD2 as a potential therapeutic target in SHH-MB and silencing FANCD2 could sensitize SHH-MB cells to radiotherapy via inducing ferroptosis. © 2024 The Pathological Society of Great Britain and Ireland.

Analysis of upfront resection or stereotactic radiosurgery for local control of solid and cystic cerebellar hemangioblastomas.

OBJECTIVE: The purpose of this study was to identify rates of and risk factors for local tumor progression in patients who had undergone surgery or radiosurgery for the management of cerebellar hemangioblastoma and to describe treatments pursued following tumor progression. METHODS: The authors conducted a retrospective single-center review of patients who had undergone treatment of a cerebellar hemangioblastoma with either surgery or stereotactic radiosurgery (SRS) between 1996 and 2019. Univariate and multivariate regression analyses were performed to examine factors associated with local tumor control. RESULTS: One hundred nine patients met the study inclusion criteria. Overall, these patients had a total of 577 hemangioblastomas, 229 of which were located in the cerebellum. The surgical and SRS cohorts consisted of 106 and 123 cerebellar hemangioblastomas, respectively. For patients undergoing surgery, tumors were treated with subtotal resection and gross-total resection in 5.7% and 94.3% of cases, respectively. For patients receiving SRS, the mean target volume was 0.71 cm3 and the mean margin dose was 18.0 Gy. Five-year freedom from lesion progression for the surgical and SRS groups was 99% and 82%, respectively. The surgical and SRS cohorts contained 32% versus 97% von Hippel-Lindau tumors, 78% versus 7% cystic hemangioblastomas, and 12.8- versus 0.56-cm3 mean tumor volumes, respectively. On multivariate analysis, factors associated with local tumor progression in the SRS group included older patient age (HR 1.06, 95% CI 1.03-1.09, p < 0.001) and a cystic component (HR 9.0, 95% CI 2.03-32.0, p = 0.001). Repeat SRS as salvage therapy was used more often for smaller tumor recurrences, and no tumor recurrences of < 1.0 cm3 required additional salvage surgery following repeat SRS. CONCLUSIONS: Both surgery and SRS achieve high rates of local control of hemangioblastomas. Age and cystic features are associated with local progression after SRS treatment for cerebellar hemangioblastomas. In cases of local tumor recurrence, salvage surgery and repeat SRS are valid forms of treatment to achieve local tumor control, although resection may be preferable for larger recurrences.

Rupture of a flow aneurysm secondary to spontaneous extracranial to intracranial revascularisation in the posterior fossa following radiation-induced vasculopathy for cerebellar tumour.

Paediatric patients receiving cranial irradiation therapy for brain tumours are at increased risk of cerebrovascular complications. Radiation-induced moyamoya syndrome (MMS) is a well-recognised complication of this. We present a case of an 8-year-old boy with a history of medulloblastoma, who underwent surgical excision followed by post-operative adjuvant oncological treatment. Six years later, he developed cerebellar/intraventricular haemorrhage. He underwent an emergency external ventricular drain (EVD) insertion followed by posterior fossa suboccipital craniotomy. On dural opening, an abnormal vessel was visualised on the surface of the right cerebellar hemisphere, which was not disturbed. No obvious abnormalities were identified intra-operatively. Cerebral catheter angiography confirmed the presence of a right-sided occipital artery (OA) to posterior inferior cerebellar artery (PICA) extracranial to intracranial (EC-IC) bypass with a zone of the distal PICA territory supplied by this EC-IC bypass. A presumed flow aneurysm originated from the bypass in the distal PICA, identified as cause for the haemorrhage. We highlight a rare cause for intracranial haemorrhage in this cohort of patients. Children who have undergone radiotherapy may have exquisitely sensitive cerebral vasculature and need careful vigilance and evaluation for vasculopathic complications following spontaneous haemorrhage.

Late effects of medulloblastoma treatment: multidisciplinary approach of survivors.

PURPOSE: Medulloblastoma is one of the brain tumors with increased life expectancy due to improvements in treatment approaches. Besides the promising results, various undesirable effects can be encountered. This study's aim is to review long-term follow-up outcomes of our cases with medulloblastoma. METHODS: Age at diagnosis, histological type of medulloblastoma, resection extension, chemotherapy and radiotherapy schemes, follow-up duration, and endocrinological, neuropsychiatric, cardiological, auditory, and visual examination results were evaluated in 20 patients diagnosed between 2007 and 2018 and followed 5 years and more. RESULTS: Twenty of 53 patients were included to the study. Eleven (55%) were male. Mean age at diagnosis was 6.95 years; mean age at the time of the study was 14 years. Mean follow-up time was 8.95 years. In terms of surgery, 14 (70%) were gross total, 1 (5%) was near total, and 2 (10%) were subtotal resection. In histopathological examination, 14 (70%) were classical medulloblastoma, 4 (20%) were desmoplastic medulloblastoma, and 1 (5%) was anaplastic medulloblastoma. With regard to endocrinological evaluation, 15 (75%) patients had hypothyroidism, 5 (25%) had growth hormone deficiency, 7 (35%) had clinical growth hormone deficiency, and 5 (25%) had sex hormone disorders. In neuropsychiatric examination, 11 (55%) patients had neurological sequelae, 18 (90%) patients had psychiatric issues, and 14 (70%) patients had two or more neuropsychiatric problems simultaneously. One (5%) patient had mitral valve insufficiency. Twelve patients (60%) had hearing loss. According to visual examination, 6 (30%) patients had refraction problem, 4 (20%) had cataract, and 1 (5%) had dry eye. CONCLUSION: Careful monitoring of long-term side effects is important for improving the quality of life of medulloblastoma patients. Besides endocrinological and other somatic sequelae of the disease and treatment, increased neuropsychiatric problems showed us that only cure is not the issue while treating childhood medulloblastoma.

Proton Therapy Mediates Dose Reductions to Brain Structures Associated With Cognition in Children With Medulloblastoma.

PURPOSE: Emerging evidence suggests proton radiation therapy may offer cognitive sparing advantages over photon radiation therapy, yet dosimetry has not been compared previously. The purpose of this study was to examine dosimetric correlates of cognitive outcomes in children with medulloblastoma treated with proton versus photon radiation therapy. METHODS AND MATERIALS: In this retrospective, bi-institutional study, dosimetric and cognitive data from 75 patients (39 photon and 36 proton) were analyzed. Doses to brain structures were compared between treatment modalities. Linear mixed-effects models were used to create models of global IQ and cognitive domain scores. RESULTS: The mean dose and dose to 40% of the brain (D40) were 2.7 and 4.1 Gy less among proton-treated patients compared with photon-treated patients (P = .03 and .007, respectively). Mean doses to the left and right hippocampi were 11.2 Gy lower among proton-treated patients (P < .001 for both). Mean doses to the left and right temporal lobes were 6.9 and 7.1 Gy lower with proton treatment, respectively (P < .001 for both). Models of cognition found statistically significant associations between higher mean brain dose and reduced verbal comprehension, increased right temporal lobe D40 with reduced perceptual reasoning, and greater left temporal mean dose with reduced working memory. Higher brain D40 was associated with reduced processing speed and global IQ scores. CONCLUSIONS: Proton therapy reduces doses to normal brain structures compared with photon treatment. This leads to reduced cognitive decline after radiation therapy across multiple intellectual endpoints. Proton therapy should be offered to children receiving radiation for medulloblastoma.

IFN-γ promotes radioresistant Nestin-expressing progenitor regeneration in the developing cerebellum by augmenting Shh ligand production.

BACKGROUND: Patients with brain tumors, especially pediatric brain tumors such as cerebellar medulloblastoma, always suffer from the severe side effects of radiotherapy. Regeneration of neural cells in irradiation-induced cerebellar injury has been reported, but the underlying mechanism remains elusive. METHODS: We established an irradiation-induced developing cerebellum injury model in neonatal mice. Microarray, KEGG analysis and semi in vivo slice culture were performed for mechanistic study. RESULTS: Nestin-expressing progenitors (NEPs) but not granule neuron precursors (GNPs) were resistant to irradiation and able to regenerate after irradiation. NEPs underwent less apoptosis but similar DNA damage following irradiation compared with GNPs. Subsequently, they started to proliferate and contributed to granule neurons regeneration dependent on the sonic hedgehog (Shh) pathway. In addition, irradiation increased Shh ligand provided by Purkinje cells. And microglia accumulated in the irradiated cerebellum producing more IFN-γ, which augmented Shh ligand production to promote NEP proliferation. CONCLUSIONS: NEP was radioresistant and regenerative. IFN-γ was increased post irradiation to upregulate Shh ligand, contributing to NEP regeneration. Our study provides insight into the mechanisms of neural cell regeneration in irradiation injury of the developing cerebellum and will help to develop new therapeutic targets for minimizing the side effects of radiotherapy for brain tumors.

Single-fraction Radiation Treatment Dose Response in a Genetically Engineered Mouse Model of Medulloblastoma.

Medulloblastoma is the most common malignant brain tumor of children. Although standard of care radiotherapy for pediatric medulloblastoma (PM) can lead to long-term remission or cure in many patients, it can also cause life-long cognitive impairment and other adverse effects. The pathophysiological mechanisms involved in radiation-induced cerebral damage are incompletely understood, and their elucidation may lead to interventions that mitigate radiation toxicity. To explore the mechanisms of radiation-induced cerebral damage, transgenic mouse models of PM and non-tumor-bearing controls were exposed to radiation doses that ranged from 0 to 30 Gy. Between 0-20 Gy, a significant dose-dependent reduction in tumor-associated hydrocephalus and increase in overall survival were observed. However, at 30 Gy, hydrocephalus incidence increased and median overall survival fell to near-untreated levels. Immunohistochemistry revealed that both tumor-bearing and non-tumor-bearing mice treated with 30 Gy of radiation had significantly more reactive astrocytes and microvascular damage compared to untreated controls. This effect was persistent across mice that were given 1 and 2 weeks of recovery time after irradiation. Our data suggest that radiation therapy promotes neural death by inducing long-term neuroinflammation in PM, suggesting radiation delivery methods that limit inflammation may be effective at widening the therapeutic window of radiation therapy in PM patients.

Subtyping of Group 3/4 medulloblastoma as a potential prognostic biomarker among patients treated with reduced dose of craniospinal irradiation: a Japanese Pediatric Molecular Neuro-Oncology Group study.

BACKGROUND: One of the most significant challenges in patients with medulloblastoma is reducing the dose of craniospinal irradiation (CSI) to minimize neurological sequelae in survivors. Molecular characterization of patients receiving lower than standard dose of CSI therapy is important to facilitate further reduction of treatment burden. METHODS: We conducted DNA methylation analysis using an Illumina Methylation EPIC array to investigate molecular prognostic markers in 38 patients with medulloblastoma who were registered in the Japan Pediatric Molecular Neuro-Oncology Group and treated with reduced-dose CSI. RESULTS: Among the patients, 23 were classified as having a standard-risk and 15 as high-risk according to the classic classification based on tumor resection rate and presence of metastasis, respectively. The median follow-up period was 71.5 months (12.0-231.0). The median CSI dose was 18 Gy (15.0-24.0) in both groups, and 5 patients in the high-risk group received a CSI dose of 18.0 Gy. Molecular subgrouping revealed that the standard-risk cohort included 5 WNT, 2 SHH, and 16 Group 3/4 cases; all 15 patients in the high-risk cohort had Group 3/4 medulloblastoma. Among the patients with Group 3/4 medulloblastoma, 9 of the 31 Group 3/4 cases were subclassified as subclass II, III, and V, which were known to an association with poor prognosis according to the novel subtyping among the subgroups. Patients with poor prognostic subtype showed worse prognosis than that of others (5-year progression survival rate 90.4% vs. 22.2%; p < 0.0001). The result was replicated in the multivariate analysis (hazard ratio12.77, 95% confidence interval for hazard ratio 2.38-99.21, p value 0.0026 for progression-free survival, hazard ratio 5.02, 95% confidence interval for hazard ratio 1.03-29.11, p value 0.044 for overall survival). CONCLUSION: Although these findings require validation in a larger cohort, the present findings suggest that novel subtyping of Group 3/4 medulloblastoma may be a promising prognostic biomarker even among patients treated with lower-dose CSI than standard treatment.

Medulloblastomas in Pediatric and Adults.

Medulloblastoma is the primary malignant embryonic tumor of the cerebellum and the most common malignant tumor of childhood, accounting up to 25% of all CNS tumors in children, but is extremely rare in adults. Despite the fact that medulloblastomas are one of the most malignant human tumors, it is worthy to note that a great breakthrough has been achieved in our understanding of oncogenesis and the development of real methods of treatment. The main objective of surgical treatment is a maximum resection of tumor with minimal impairment of neurological functions, in order to reduce the volume, remove tumor tissue, get the biopsy, and restore the cerebrospinal fluid flow. The progress of surgical techniques (using a microscope, ultrasound suction), anesthesiology, and intensive care has significantly decreased surgical mortality and increased radicality of tumor removal. Postoperative mortality is less than one percent in most studies, while neurological complications have been reported between 5-10%. Radiotherapy is the main method of treatment in patients older than 3 years, which dramatically improved the recurrence-free survival. Nevertheless, the radiation therapy without systemic chemotherapy leads to a high risk of systemic metastases. After the role of chemotherapy was statistically proven, investigations of the optimal combination of different chemotherapy regimens continued around the world. Currently, 80% of patients can already be cured, however, the quality of life of patients in the long-term period remains quite low, which depends on many factors including endocrinological, cognitive, neurological, and otoneurologic aspects. Thus, the main strategic goal of the development of neuro-oncology is to reduce the doses of radiation therapy to the CNS and the main task of international research is to optimize existing protocols and develop fundamentally new ones based on molecular genetic research in order to improve the quality of life.

A Pilot Study Omitting Radiation in the Treatment of Children with Newly Diagnosed Wnt-Activated Medulloblastoma.

PURPOSE: Treatment of wingless (WNT)-activated medulloblastoma (WNT+MB) with surgery, irradiation (XRT), and chemotherapy results in excellent outcomes. We studied the efficacy of therapy de-intensification by omitting XRT entirely in children with WNT+MB. PATIENTS AND METHODS: Tumors were molecularly screened to confirm the diagnosis of WNT+MB. Eligible children were treated within 31 days following surgery with nine cycles of adjuvant chemotherapy per ACNS0331. No XRT was planned. The primary endpoint was the occurrence of relapse, progression, or death in the absence of XRT within the first two years after study enrollment. Four events in the first 10 evaluable patients would result in early study closure. RESULTS: Fourteen children were prescreened, and nine met the protocol definition of WNT+MB. Six of the nine eligible patients consented to protocol therapy, and five completed planned protocol therapy. The first two children enrolled relapsed shortly after therapy completion with local and leptomeningeal recurrences. The study was closed early due to safety concerns. Both children are surviving after XRT and additional chemotherapy. A third child relapsed at completion of therapy but died of progressive disease 35 months from diagnosis. Two children finished treatment but immediately received post-treatment XRT to guard against early relapse. The final child's treatment was aborted in favor of a high-dose therapy/stem cell rescue approach. Although OS at 5 years is 83%, no child received only planned protocol therapy, with all receiving eventual XRT and/or alternative therapy. CONCLUSIONS: Radiotherapy is required to effectively treat children with WNT-altered medulloblastoma. See related commentary by Gottardo and Gajjar, p. 4996.

In Vivo Radiobiological Investigations with the TOP-IMPLART Proton Beam on a Medulloblastoma Mouse Model.

Protons are now increasingly used to treat pediatric medulloblastoma (MB) patients. We designed and characterized a setup to deliver proton beams for in vivo radiobiology experiments at a TOP-IMPLART facility, a prototype of a proton-therapy linear accelerator developed at the ENEA Frascati Research Center, with the goal of assessing the feasibility of TOP-IMPLART for small animal proton therapy research. Mice bearing Sonic-Hedgehog (Shh)-dependent MB in the flank were irradiated with protons to test whether irradiation could be restricted to a specific depth in the tumor tissue and to compare apoptosis induced by the same dose of protons or photons. In addition, the brains of neonatal mice at postnatal day 5 (P5), representing a very small target, were irradiated with 6 Gy of protons with two different collimated Spread-Out Bragg Peaks (SOBPs). Apoptosis was visualized by immunohistochemistry for the apoptotic marker caspase-3-activated, and quantified by Western blot. Our findings proved that protons could be delivered to the upper part while sparing the deepest part of MB. In addition, a comparison of the effectiveness of protons and photons revealed a very similar increase in the expression of cleaved caspase-3. Finally, by using a very small target, the brain of P5-neonatal mice, we demonstrated that the proton irradiation field reached the desired depth in brain tissue. Using the TOP-IMPLART accelerator we established setup and procedures for proton irradiation, suitable for translational preclinical studies. This is the first example of in vivo experiments performed with a "full-linac" proton-therapy accelerator.

Molecular characterization of long-term survivors of metastatic medulloblastoma treated with reduced-dose craniospinal irradiation.

BACKGROUND AND AIMS: Current standard treatment for metastatic medulloblastoma consists of 36 Gray (Gy) of craniospinal irradiation (CSI) supplemented with local irradiation and adjuvant chemotherapy after surgery. Although contemporary protocols have been designed to limit a radiation dose using risk-adapted CSI dosing to reduce neurocognitive morbidity, high-dose CSI remains the standard of care. Recently, the molecular classification of medulloblastoma has been emerging but its clinical significance has not been established particularly in patients with metastatic medulloblastoma treated with lower dose of CSI. METHODS: We molecularly analyzed three cases of metastatic medulloblastoma treated with 24.0 Gy of CSI by DNA methylation analysis using the Illumina EPIC array. RESULTS: All three patients had spinal metastases at the time of diagnosis. Postoperative treatment included multiple courses of chemotherapy, 24 Gy of CSI with focal boost to primary and metastatic sites, and high-dose chemotherapy. There was no disease progression observed during the 9.0, 7.7, and 5.7　years post-diagnosis follow-up. The molecular diagnosis was Group 3/4 in all three cases. Cases 1 and 2 belonged to Subtypes 7 and 4, both of which were reported to be good prognostic subtypes among the group. Case 3 belonged to Subtype 5 with MYC amplification. CONCLUSIONS: The present cases suggest that the novel subtype classification in Group 3/4 medulloblastoma may be useful for risk stratification of patients with metastatic medulloblastoma who received lower dose of CSI than standard treatment.

Prognostic factors affecting infantile medulloblastoma outcomes in the molecular era: a 12-year single-center experience from Egypt.

Aims: To assess the clinical, pathological and molecular characteristics (Sonic hedgehog and group 3/4 molecular subtypes expression) and treatment modalities for infantile medulloblastoma in correlation with outcomes. Materials & methods: A retrospective study of 86 medulloblastoma patients (≤3 years) was conducted. M0 patients <2.5 years received four cycles of chemotherapy followed by focal radiotherapy (FRT) and chemotherapy. Between 2007 and 2015, Metastatic patients <2.5 years received craniospinal irradiation (CSI) after the end of chemotherapy. After 2015, metastatic patients <2.5 years received CSI postinduction. Results: The hazard ratio for death was significantly higher in the FRT (HR = 2.8) group compared with the CSI group (hazard ratio = 1). Metastatic disease significantly affected the overall survival of the Sonic hedgehog group and the overall survival and event-free survival of group 3/4. Conclusion: Metastatic disease had a significant impact on outcomes. FRT is not effective in treating infantile medulloblastoma.

This study aimed to analyze the management of and prognostic factors affecting the outcomes of 86 young children (<3 years of age at presentation) diagnosed with medulloblastoma, an aggressive brain tumor that is commonly seen in this age group. All children had surgical operations aiming at resecting their tumors, followed by chemotherapy and irradiation. Study results showed that disease disseminated into the nervous system was associated with poorer outcomes compared with localized disease. Administration of local irradiation to the primary tumor site in the brain only, without exposing the spinal cord to radiotherapy, was associated with a higher risk of death.