Real-world longitudinal data documenting the diagnostic impact of DNA methylation array (MA) profiling in pediatric ependymoma remain sparse. We report a single-center retrospective analysis evaluating MA-driven reclassification, molecular subgroup distribution, and long-term survival outcomes in a national pediatric referral cohort. Sixty-three pediatric patients with a histological ependymoma diagnosis treated at Motol and Homolka University Hospital (2010–2025) were included. DNA methylation profiling, RNA sequencing, copy number variation and t-SNE analysis were performed. Survival was estimated by the Kaplan–Meier method. MA confirmed ependymoma in 48 patients (76.2

Cancer is the leading cause of disease-related deaths among children in high-income countries. Tumor heterogeneity and lack of mechanism-of-action-based therapeutic options are key challenges to overcome in order to improve pediatric cancer patients survival. Here, we report the EU-IMI-2 funded public-private partnership - ITCC-Pediatric Preclinical Proof-of-Concept Platform (ITCC-P4)-, which has built a large repertoire of patient-derived xenograft (PDX) models, representing all major solid pediatric cancer types, for in vivo drug testing. Three-hundred-fifty-three PDX models from diagnostic and relapsed pediatric cancers have been established and molecularly characterized, together with matched germline/tumor samples. As proof-of-concept, we present in vivo drug screening data in neuroblastoma and rhabdomyosarcoma models. PDX data, accessible at http://r2platform.com/itcc-p4, allow the selection of models based on oncogenic drivers and/or potential biomarkers for preclinical testing. Operated by a non-profit entity (www.itccp4.com), this sustainable platform aids academic and industrial researchers in developing and prioritizing innovative therapies for pediatric cancer. ### Competing Interest Statement Stefan Pfister, Co-founder and shareholder Heidelberg Epignostix GmbH Natalie Jaeger is a full-time employee of Heidelberg Epignostix GmbH Martin Sill, Co-founder and shareholder Heidelberg Epignostix GmbH Jens Hoffmann: Shareholder EPO Experimental Pharmacology & Oncology Berlin-Buch GmbH Justyna Wierzbinska and Andreas Schlicker are employees of Bayer AG. Andreas Schlicker is a shareholder of Bayer AG. Petra Hamerlik provides consultancy for LindonLight Collective and Rakobina Therapeutics. Stefano Cairo is now a full-time employee of Champions Oncology, Rockville, Maryland, USA David Shields is an employee of Pfizer Inc and holds shares in the company. Maureen M. Hattersley is an employee of AstraZeneca and holds shares in the company. Employees from the following pharmaceutical companies also contributed as co-authors to the ITCC-P4 consortium project, as stated in their affiliations: LILLY, ROCHE, PFIZER, BAYER ,PHARMA MAR, CHARLES RIVER, JANSSEN, AZ, AMGEN, SERVIER, SANOFI.

Cancer is the leading cause of disease-related deaths among children in high-income countries. Tumor heterogeneity and lack of mechanism-of-action-based therapeutic options are key challenges to overcome to improve pediatric cancer patient survival. To address these challenges, we formed the EU-IMI-2 funded public-private partnership "ITCC-Pediatric Preclinical Proof-of-Concept Platform" (ITCC-P4), which built a large repertoire of patient-derived xenograft (PDX) models representing all major high-risk solid pediatric cancer types for in vivo drug testing. A total of 353 PDX models were established from diagnostic and relapsed pediatric cancers and molecularly characterized, together with matched germline/tumor samples. Serial PDX models were also established, spanning diagnostic/posttreatment, primary/relapse, and metastasis-derived pairs. Proof-of-concept in vivo drug screening data in neuroblastoma and rhabdomyosarcoma models identified potential predictive biomarkers for targeted therapy. Molecular data from the PDX models, accessible at https://r2platform.com/itcc-p4, allowed the selection of models for preclinical testing based on oncogenic drivers and/or potential biomarkers. Operated by a non-profit entity, this sustainable platform aids academic and industrial researchers in developing and prioritizing innovative therapies for pediatric cancer.

Pediatric low-grade gliomas (pLGG) are the most common group of childhood brain tumors. Genetic alterations in the RAS-RAF-mitogen-activated protein kinase (MAPK) pathway are the molecular drivers in the vast majority of pLGG. A large proportion of pediatric pLGG are characterized by the presence of fusion genes. An institutional molecular analysis together with an RNA-NGS study was performed to reveal LGG-associated molecular alterations. In our cohort of pLGG patients, molecular alterations were identified in 318 out of 342 cases (92.9%) through a combination of RT-PCR, Sanger sequencing, and NGS methodologies. Fusion events were independently called using three fusion callers: Archer Analysis 6.0 and/or 7.0, Arriba version 2.4, and STAR-Fusion 24. Among these, STAR-Fusion had the lowest sensitivity, detecting rearrangements in only 67% of fusion-positive cases. In contrast, Arriba detected rearrangements in 97.77% of cases, while Archer detected rearrangements in 88.6% of cases. These findings highlight differences in detection efficiency among fusion callers, emphasizing the importance of tool selection in molecular diagnostics. The detection of fusion genes is very important for correct diagnosis, prognosis, and adequate targeted treatment.

The increasing availability of advanced neuroimaging has led to a rise in incidental findings among pediatric patients. Management strategies include immediate surgical intervention, observation or surgery upon progression. These are influenced by imaging characteristics, lesion behavior over time, patient/family preferences, and the lesion's surgical risks. The thalamus's eloquent location often warrants a more conservative approach. Identifying features predictive of growth could help inform clinical decisions regarding surveillance and potential intervention. We retrospectively analyzed 44 pediatric patients with 46 thalamic incidentalomas, assessing radiological characteristics, temporal changes, and factors predictive of progression. Progression was defined as a change in size and/or new/increased contrast enhancement. Prognostic factors for progression (demographics, initial tumor volume, extension beyond thalamus, changes in enhancement, margin characteristics) were assessed for significance. Of 46 incidentalomas, 40 were followed longitudinally. Nine incidentalomas (22.5%) showed regression, while nine (22.5%) progressed. The average time to regression was 947 days, and to progression, 516 days. Three patients underwent biopsy due to progressive changes; each was diagnosed with low-grade glioma. Statistical analysis revealed that initial incidentaloma volume, extension beyond the thalamus, and contrast enhancement were significantly associated with progression (p = 0.025, p < 0.001, and p = 0.001, respectively). Most pediatric thalamic incidentalomas are small, stable, and likely low-grade. However, approximately one-fifth exhibit progressive features, warranting prolonged surveillance. Larger initial volume, extra-thalamic extension, and contrast enhancement are significant predictors of progression and may justify earlier intervention. Individualized management remains essential, balancing natural history with surgical risk.

PURPOSE:The specifics of biological behavior, anatomical localization, treatment, decision-making, and long-term prognosis in neonatal and infantile intracranial tumors have not been well studied. METHODS:A retrospective monocentric study of patients aged ≤ 12 months treated for an intracranial tumor over a 23-year period was performed. Data regarding the survival rate according to the tumor histology were evaluated in further detail. RESULTS:A total of 63 patients with a median age of 200 days at the first admission (interquartile range (IQR) = 118-301 days) were analyzed. Most tumors were supratentorial (67.7%). Overall survival according to histopathological subgroups of included tumors was the most favorable in the low-grade glioma subgroup with 1- and 3-year survival of 96% (95% confidence interval [CI] = 88.6-100%) and 88% (95% CI = 76.1-100%), while the 3-year survival for the embryonal tumors subgroup was 15% (95% CI = 4.2-53.4%). Mortality in the cohort reached 42.8% with the median time to death of 6 months (IQR = 1-12 months). CONCLUSION:Infantile and neonatal primary CNS tumors significantly vary from CNS tumors in older pediatric patients both in their localization, distribution of histopathological subtypes, and the presence of mutations specific to these tumors, providing useful therapeutic targets. Brain tumors in children under 1 year of age are scarce compared to other pediatric brain tumors.

Abstract BACKGROUND The etiology of pediatric cancer remains largely unclear, with only a small proportion of patients (8-10%) harboring cancer predisposition syndromes (CPS). However, prospective studies evaluating CPS in pediatric neuro-oncology patients are scarce. We aimed to investigate the incidence and spectrum of CPS in this patient population. METHODS Newly diagnosed pediatric brain tumor patients from 2020 to 2023 were consented, and their germline DNA was sequenced using a DNA panel for next-generation sequencing (NGS) or whole-exome sequencing. Patients with previously known NF1, NF2, or TSC were excluded from the study. RESULTS A total of 164 consecutive patients from our center were enrolled over four years. Pathogenic germline variants (UV4 or UV5) were detected in 24 cases (14.6%). Half of these mutated genes are known to be associated with pediatric tumors. Examples include variants in TP53 (two patients with high-grade glioma), biallelic FANCD1 (medulloblastoma), SMARCE1 (meningioma), NF1 (high-grade glioma), NF2 (meningioma), MSH2 (medulloblastoma), and others. The second group of patients harbored pathogenic variants without confirmed associations with pediatric cancer, including heterozygous variants in MUTYH (n=3), FANC genes (n=2), NBN (n=2), PALB2, XPC, and pathogenic variants in WRN or CHEK2 (n=3). In addition to pathogenic variants in CHEK2, variants of uncertain significance, such as c.470T>C, were also identified (total n=8). The majority of patients with a CHEK2 variant were diagnosed with glial tumors. Notably, 8.3% of patients with pediatric low-grade gliomas (LGG) from our cohort harbored a CHEK2 germline variant. CONCLUSIONS The incidence of CPS in our cohort (14.6%) is higher than what is reported in studies evaluating all pediatric cancer patients. This percentage might be underestimated due to the exclusion of known phacomatoses. The role of some variants, including those in CHEK2, warrants further investigation. This study was supported by the Ministry of Health of the Czech Republic, grant number NU21-07-00419.

Diffuse pediatric-type high-grade gliomas (pedHGG), H3- and IDH-wildtype, encompass three main DNA-methylation-based subtypes: pedHGG-MYCN, pedHGG-RTK1A/B/C, and pedHGG-RTK2A/B. Since their first description in 2017 tumors of pedHGG-RTK2A/B have not been comprehensively characterized and clinical correlates remain elusive. In a recent series of pedHGG with a Gliomatosis cerebri (GC) growth pattern, an increased incidence of pedHGG-RTK2A/B (n = 18) was observed. We added 14 epigenetically defined pedHGG-RTK2A/B tumors to this GC series and provided centrally reviewed radiological, histological, and molecular characterization. The final cohort of 32 pedHGG-RTK2A/B tumors consisted of 25 pedHGG-RTK2A (78

BACKGROUND The etiology of pediatric cancer remains largely unclear, with only a small proportion of patients (8-10%) harboring cancer predisposition syndromes (CPS). However, prospective studies evaluating CPS in pediatric neuro-oncology patients are scarce. We aimed to investigate the incidence and spectrum of CPS in this patient population. METHODS Newly diagnosed pediatric brain tumor patients from 2020 to 2023 were consented, and their germline DNA was sequenced using a DNA panel for next-generation sequencing (NGS) or whole-exome sequencing. Patients with previously known NF1, NF2, or TSC were excluded from the study. RESULTS A total of 164 consecutive patients from our center were enrolled over four years. Pathogenic germline variants (UV4 or UV5) were detected in 24 cases (14.6%). Half of these mutated genes are known to be associated with pediatric tumors. Examples include variants in TP53 (two patients with high-grade glioma), biallelic FANCD1 (medulloblastoma), SMARCE1 (meningioma), NF1 (high-grade glioma), NF2 (meningioma), MSH2 (medulloblastoma), and others. The second group of patients harbored pathogenic variants without confirmed associations with pediatric cancer, including heterozygous variants in MUTYH (n=3), FANC genes (n=2), NBN (n=2), PALB2, XPC, and pathogenic variants in WRN or CHEK2 (n=3). In addition to pathogenic variants in CHEK2, variants of uncertain significance, such as c.470T>C, were also identified (total n=8). The majority of patients with a CHEK2 variant were diagnosed with glial tumors. Notably, 8.3% of patients with pediatric low-grade gliomas (LGG) from our cohort harbored a CHEK2 germline variant. CONCLUSIONS The incidence of CPS in our cohort (14.6%) is higher than what is reported in studies evaluating all pediatric cancer patients. This percentage might be underestimated due to the exclusion of known phacomatoses. The role of some variants, including those in CHEK2, warrants further investigation. This study was supported by the Ministry of Health of the Czech Republic, grant number NU21-07-00419.

Craniospinal irradiation with boost to primary tumor site (and metastatic sites) is current radiotherapy standard for most patients diagnosed with medulloblastoma (MB). This treatment is effective, but survivors frequently develop long-term toxicity affecting the quality of life. Proton radiotherapy has the same efficacy compared to conventional photon-based techiques, but might achieve lower risk of toxicity. We retrospectivelly analyzed our cohort of patients irradiated for MB in our institution, using IMPT (intensity modulated proton therapy). Between May 2013 and December 2023 eighty patients (50 male, 30 female, median age at radiotherapy 8 years/range 3-17/) with primary or recurrent MB (not previously irradiated) were treated and included into analysis. 36 patients were treated for high-risk MB (mostly metastatic), 44 pts for SR disease. Neoadjuvant, concurrent and adjuvant systemic treatment was applied according to the protocol selected by the pediatric oncologist. All but one patients completed their treatment, acute toxicity including hematological was mild and lead to treatment interruption in seven cases. With a median of follow-up 39,6 months (range 3-119) 62 pts were in complete remission, 3 pts alive with disease, 14 died from disease progression and one died from complication (intracranial hemorrhage). We were able to identify two secondary malignancies potentially associated with IMPT (thyroid cancer, radiation induced high-grade glioma). Most common endocrinopathy observed in our patients was hypothyroidism and growth-hormon decifit. Due to lack of data, we were not able to analyze cognitive functions and quality of life. There was one case of severe brainstem necrosis with persistent neurological deficit, treated with corticosteroids and bevacizumab. Proton radiotherapy using IMPT for craniospinal irradiation in MB is feasible, treatment outcomes and toxicity are encouraging, although a longer follow-up is needed.

Late events after radiation therapy for primary brain tumors consist of secondary malignant neoplasms (SMN) and tumor recurrences. The incidence and biology of late events are not very well described. Therefore, we aimed to identify late events in our institutional cohort and describe their biology. A retrospective chart review of all irradiated pediatric brain tumor patients treated between 2000 and 2015 at our institution was performed to obtain demographics and clinical data of late events. Late events were defined as intracranial intraaxial SMN or tumor recurrence occurring later than 3 years after radiation therapy. A whole-genome methylation array was employed to identify the methylation class of the late event. In the observed period, 267 patients received some form of cranial radiotherapy for primary brain tumor; high-grade glioma (HGG, n=66), medulloblastoma (n=74), ependymoma (n=50), germ-cell tumors (GCT, n=22), low-grade glioma (LGG, n=24), and other diagnoses (n=31). Out of the 174 patients who were alive and without an event after 3 years from the radiation therapy, 30 developed late events (16.8%), and 27 of them were histologically verified. Verified late events consisted of 8 SMNs (29.6%) and 19 primary tumor recurrences. SMNs were mainly radiation-induced gliomas (RIG, n=7) and one atypical teratoid/rhabdoid tumor (ATRT) after craniopharyngioma. All RIG tumors clustered with the “pediatricHGG_RTK1” methylation class. Tumor recurrences consisted of medulloblastomas (Group 4 and Wnt), ependymomas (PFA and ST_ZFTA), GCTs, gliomas (one NF1-associated HGG, one H3-altered thalamic glioma, one diffuse astrocytoma with BRAF-V600E mutation), and craniopharyngiomas. The overall survival rate 5 years after a late event was 39.7%, with a worse survival rate for SMN patients (14.3%) compared to those with recurrences (44.9%) (p=0.05). Late events affected 16.8% of long-term survivors. Strikingly, SMNs represented almost 30% of late events and were associated with a very poor prognosis.

Abstract BACKGROUND Rhabdoid-Tumor-Predisposition-Syndrome is due to germline mutations in SMARCB1 (rarely SMARCA4). We pursued a comprehensive clinical and (epi-)genetic characterization of RTPS families. METHODS 90 affected children from 16 countries were compared to 252 with sporadic rhabdoid tumors (01/2004 - 01/2021). Tumors and blood were examined for structural or single nucleotide variants (SV, SNV) in SMARCB1/SMARCA4. In 83% (70/84) of RTPS1-patients complete genetic data were available. Trio-exome (n=25) and 850k-methylation analysis of tumors (52/84) and blood (n=51), parents (n=44) and unaffected siblings (n=4) was performed. RESULTS RTPS1 and 2 were diagnosed in 84 (48 females, 36 males) and 6 patients respectively. Median age at diagnosis (RTPS1 only) was 5 (0 – 203) months (18 months, 0-211 in controls, p<0,001). ATRT were present in 55% (46/84), extracranial, extrarenal malignant RT (eMRT) and RT of the kidney (RTK) in 8% (7/84). 26% (22/84) presented with synchronous tumors (SYN). Homozygous SVs were less frequent in the RTPS-tumors [20% (14/84) vs 47% (82/174), p<0,001]. ATRT-MYC was significantly more common among RTPS1 while ATRT-SHH was less common. Trio blood DNA-methylation analysis separated samples of parents but not siblings from RTPS patients. Likely (DNA-methylation) age was a major confounder. The analysis of trio-exomes is ongoing. 5-year-OS and -EFS in RTPS1-patients were 18,4±4.5% and 14±3,9%, (controls: 48,2 ±3,5%, 40,3±3,2%). VOD (venoocclusive disease) was significant in patients < 2 months [18,5% (12/65) vs. 3,3% (3/92), p=0.005]. RTPS1-patients rarely achieved a CR [32% (27/84) vs. 52% (129/249), p=0,002]. In an adjusted multivariate model prognostic factors were male sex [HR: 1.7 (1.0 – 2.9)], age ≤12 months [HR: 2.1 (1.0 – 4.3)], and diagnosis of ATRT [HR: 0.6 (0.3 – 0.9)]. CONCLUSION We describe significant positive outcome predictors such as age >12 months, absence of SYN, diagnosis of ATRT, localized disease, PGV located at C-termini and female sex in RTPS1-patients.

In this study, we provide a comprehensive clinical and molecular biological characterization of radiation-induced gliomas (RIG), including a risk assessment for developing gliomas. A cohort of 12 patients who developed RIG 9.5 years (3–31 years) after previous cranial radiotherapy for brain tumors or T-cell acute lymphoblastic leukemia was established. The derived risk of RIG development based on our consecutive cohort of 371 irradiated patients was 1.6% at 10 years and 3.02% at 15 years. Patients with RIG glioma had a dismal prognosis with a median survival of 7.3 months. We described radiology features that might indicate the suspicion of RIG rather than the primary tumor recurrence. Typical molecular features identified by molecular biology examination included the absence of Histon3 mutation, methylation profile of pedHGG-RTK1 and the presence of recurrent PDGFRA amplification and CDKN2A/B deletion. Of the two long-term surviving patients, one had gliomatosis cerebri, and the other had pleomorphic xanthoastrocytoma with BRAF V600E mutation. In summary, our experience highlights the need for tissue diagnostics to allow detailed molecular biological characterization of the tumor, differentiation of the secondary tumor from the recurrence of the primary disease and potentially finding a therapeutic target.

BACKGROUND:The term gliomatosis cerebri (GC), a radiology-defined highly infiltrating diffuse glioma, has been abandoned since molecular GC-associated features could not be established. METHODS:We conducted a multinational retrospective study of 104 children and adolescents with GC providing comprehensive clinical and (epi-)genetic characterization. RESULTS:Median overall survival (OS) was 15.5 months (interquartile range, 10.9-27.7) with a 2-year survival rate of 28%. Histopathological grading correlated significantly with median OS: CNS WHO grade II: 47.8 months (25.2-55.7); grade III: 15.9 months (11.4-26.3); grade IV: 10.4 months (8.8-14.4). By DNA methylation profiling (n = 49), most tumors were classified as pediatric-type diffuse high-grade glioma (pedHGG), H3-/IDH-wild-type (n = 31/49, 63.3%) with enriched subclasses pedHGG_RTK2 (n = 19), pedHGG_A/B (n = 6), and pedHGG_MYCN (n = 5), but only one pedHGG_RTK1 case. Within the pedHGG, H3-/IDH-wild-type subgroup, recurrent alterations in EGFR (n = 10) and BCOR (n = 9) were identified. Additionally, we observed structural aberrations in chromosome 6 in 16/49 tumors (32.7%) across tumor types. In the pedHGG, H3-/IDH-wild-type subgroup TP53 alterations had a significant negative effect on OS. CONCLUSIONS:Contrary to previous studies, our representative pediatric GC study provides evidence that GC has a strong predilection to arise on the background of specific molecular features (especially pedHGG_RTK2, pedHGG_A/B, EGFR and BCOR mutations, chromosome 6 rearrangements).

Abstract BACKGROUND Diffuse pediatric-type high-grade gliomas (pedHGG), H3-wildtype and IDH-wildtype, encompass three main methylome-based subclasses: pedHGG-MYCN, -RTK1A/B/C, and -RTK2A/B. Since their first description in 2017, tumors of pedHGG-RTK2A/B have not been further characterized and their clinical significance is unknown. METHODS A not yet published cases series on pedHGG with a gliomatosis cerebri (GC) growth pattern showed an increased incidence of pedHGG-RTK2A/B (n=18/40). We assembled a cohort of 14 additional methylation-based pedHGG-RTK2A/B tumors and pooled them with the GC tumors providing centrally reviewed radiological, histological, and molecular characterization. RESULTS Our cohort of 32 pedHGG-RTK2A/B tumors consisted of 25 RTK2A (78%) and seven RTK2B (22%) cases. The median age was 11.6 years (4-17) with an overall survival of 15.9 months (interquartile range 12.1-25.8). Of the additional unselected cases with available imaging (10 of 14), seven showed a GC phenotype at diagnosis or follow-up. In addition, pedHGG-RTK2B tumors exhibited bithalamic involvement (6/7, 86%). Histopathology confirmed a diffuse glial neoplasm in all cases with prominent angiocentric features in both subclasses. Most tumors (24/29, 83%) diffusely expressed EGFR, notably with a focal perivascular enhancement. Cells of pedHGG-RTK2A lacked Olig2 expression, whereas 43% (3/7) of pedHGG-RTK2B expressed Olig2. Loss of ATRX expression occurred in four pedHGG-RTK2B samples (57%). In sequencing analyses (RTK2A: n=18, RTK2B: n=5), EGFR alterations (n=15/23, 65%; predominantly point mutations) were commonly found in both subclasses. Mutations in BCOR (n=14/18, 78%), SETD2 (n=7/18, 39%), and TERT promoter (n=6/18, 33%) occurred exclusively in pedHGG-RTK2A tumors, while pedHGG-RTK2B tumors were enriched for TP53 mutations (4/5, 80%). CONCLUSIONS In conclusion, genotype-phenotype correlations in a multicenter series of pedHGG-RTK2A/B tumors revealed a highly diffuse-infiltrating tumor frequently exhibiting a GC phenotype. The two subclasses share particular histomolecular features (EGFR alterations, angiocentric pattern), whereas they differ in specific characteristics (pedHGG-RTK2A: Olig2 negativity, BCOR and SETD2 mutations; pedHGG-RTK2B: ATRX and TP53 alterations).

Background Tumors of fourth ventricle are frequently treated pathologies in pediatric neurosurgery. Data regarding predictors for permanent neurological deficits, long-term functional outcomes, cerebellar mutism (CM), the extent of resection (EOR), and oncological outcomes are scarce. We attempt to contribute to this topic with analysis of our institutional cohort. Methods A retrospective single-center study of patients aged ? 19 years who underwent primary surgical resection of fourth ventricular tumor over a 15-year period (2006–2021). Predictors analyzed included: age, gender, surgical approach, anatomical pattern, tumor grade, EOR, tumor volume, and others as appropriate. Results 106 patients were included (64 males, mean age 7.3 years). Rate of permanent neurological deficit was 24.2%; lateral tumor extension (p = 0.036) and tumor volume greater than 38 cm3 (p = 0.020) were significant predictors. Presence of deficit was the only significant predictor of reduced (less than 90) Lansky score (p = 0.005). CM occurred in 20.8% of patients and was influenced by medulloblastoma histology (p = 0.011), lateral tumor extension (p = 0.017), and male gender (p = 0.021). No significant difference between transvermian and telovelar approach in development of CM was detected (p = 0.478). No significant predictor was found for EOR. EOR was not found to be significant predictor of overall survival for both low-grade and high-grade tumors, however, gross total resection (GTR) was protective against tumor recurrence compared to near-total or subtotal resection (p < 0.001). Survival was found to be better in older patients (? 7.0 years, p = 0.019). Conclusion The overall rate of postoperative complications remains high due to the eloquent localization. Older patients (>7 years) have been found to have better outcomes and prognosis. Achieving GTR whenever feasible and safe has been shown to be critical for tumor recurrence. CM was more common in patients with medulloblastoma, and in patients with tumors extending through the foramen of Luschka. The telovelar approach uses a safe and anatomically sparing corridor, however, it has not been associated with a lower incidence of CM and neurological sequelae in our series, showing that each case should be assessed on an individual basis.