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PURPOSE Treatment-related toxicity after irradiation of brain tumours has been underreported in the literature. Furthermore, there is considerable heterogeneity on how and when toxicity is evaluated. The aim of this European Particle Network (EPTN) collaborative project is to develop recommendations for uniform follow-up and toxicity scoring of adult brain tumour patients treated with radiotherapy. METHODS A Delphi method-based consensus was reached among 24 international radiation-oncology experts in the field of neuro-oncology concerning the toxicity endpoints, evaluation methods and time points. RESULTS In this paper, we present a basic framework for consistent toxicity scoring and follow-up, using multiple levels of recommendation. Level I includes all recommendations that are considered minimum of care, whereas level II and III are optional evaluations in the advanced clinical or research setting, respectively. Per outcome domain, the clinical endpoints and evaluation methods per level are listed. Where relevant, the organ at risk threshold doses for recommended referral to specific organ specialists are defined. CONCLUSION These consensus-based recommendations for follow-up will enable the collection of uniform toxicity data of brain tumour patients treated with radiotherapy. With adoptation of this standard, collaboration will be facilitated and we can further propel the research field of radiation-induced toxicities relevant for these patients. An online tool to implement this guideline in clinical practice is provided at www.cancerdata.org.

Purpose Optimization of local therapies in synovial sarcoma (SS) considered unresectable at diagnosis is needed. We evaluated the effects of neoadjuvant versus adjuvant radiation versus surgery only on long-term outcomes. Methods Patients with macroscopic SS tumors before chemotherapy (IRS-group-III) in the trials CWS-81, CWS-86, CWS-91, CWS-96, CWS-2002-P and SoTiSaR-registry were analyzed. Local therapies were scheduled after 3 neoadjuvant chemotherapy cycles. Results Median age of 145 patients was 14.5 years. 106 survivors had median follow-up of 7.0 years. Tumor site was 96 extremities, 19 head–neck, 16 shoulder/hip, 14 trunk. Tumors were 10 cm in 34 patients. In a secondary resection during chemotherapy, R0-status was accomplished in 82, R1 in 30, R2 in 21 (12 missing). Radiotherapy was administered to 115 (R0 61, R1 29, R2 20, missing 5), thereof 57 before and 52 after tumor resection. 23 were treated with surgery only. For all patients, 5 year event-free (EFS) and overall survival (OS) was 68.9% ± 7.6 (95%CI) and 79.1% ± 6.9. To establish independent significance, tumor site, size, surgical results and sequencing of local therapies were analyzed in a Cox regression analysis. Variables associated with EFS and OS are site, size and sequencing of local therapies. Variables associated with local recurrence are site, surgical results and sequencing of local therapies. The only variable associated with suffering metastatic recurrence is tumor size. Conclusion Differences in sequencing of local therapy procedures are independently associated with outcomes. Best local control is achieved when tumors are irradiated pre-operatively and undergo R0 or R1 resection thereafter.

Inter-observer variation in target delineation and dose trade-off for radiotherapy of paediatric ependymoma

Glioblastoma multiforme (GBM) is the most aggressive tumor of the central nervous system with a poor prognosis. In the treatment of GBM tumors, radiotherapy plays a major role. Typically, GBM tumors cannot be cured by irradiation because of intrinsic resistance machanisms. An escalation of the irradiation dose in the GBM tumor is difficult due to the high risk of severe side effects in the brain. In the last decade, the development of new irradiation techniques, including proton-based irradiation, promised new chances in the treatment of brain tumors. In contrast to conventional radiotherapy, irradiation with protons allows a dosimetrically more confined dose deposition in the tumor while better sparing the normal tissue surrounding the tumor. A systematic comparison of both irradiation techniques on glioblastoma cells has not been performed so far. Despite the improvements in radiotherapy, it remains challenging to predict the therapeutical response of GBM tumors. Recent publications suggest extracellular vesicles (EVs) as promising markers predicting tumor response. Being part of an ancient intercellular communication system, virtually all cells release specifically composed EVs. The assembly of EVs varies between cell types and depends on environmental parameters. Here, we compared the impact of photon-based with proton-based radiotherapy on cell viability and phenotype of four different glioblastoma cell lines. Furthermore, we characterized EVs released by different glioblastoma cells and correlated released EVs with the cellular response to radiotherapy. Our results demonstrated that glioblastoma cells reacted more sensitive to irradiation with protons than photons, while radiation-induced cell death 72 h after single dose irradiation was independent of the irradiation modality. Moreover, we detected CD9 and CD81-positive EVs in the supernatant of all glioblastoma cells, although at different concentrations. The amount of released CD9 and CD81-positive EVs increased after irradiation when cells became apoptotic. Although secreted EVs of non-irradiated cells were not predictive for radiosensitivity, their increased EV release after irradiation correlated with the cytotoxic response to radiotherapy 72 h after irradiation. Thus, our data suggest a novel application of EVs in the surveillance of anti-cancer therapies. OA Förderung 2022

Purpose To examine the dosimetric feasibility of hypofractionated/dose escalated radiation therapy in patients with localized prostate carcinoma using simultaneous integrated boost intensity-modulated proton beam therapy (SIB-IMPT) in absence or presence of prostate-rectum spacer. Methods IMPT technique was implemented in 23 patients with intermediate- and high-risk prostate cancer treated at West German Proton Therapy Centre from March 2016 till June 2018, using SIB technique prescribing 60 GyRBE and 72 GyRBE in 30 fractions to PTV1 (prostate and seminal vesicle) and PTV2 boost (prostate and proximal seminal vesicle), respectively. In 15 patients, a transperineal injection of hydrogel was applied prior to radiotherapy to increase the distance between prostate and rectum. Planning and all treatments were performed with a 120 ml fluid-filled endorectal balloon customised daily for each patient. For each patient, 2 lateral IMPT beams were implemented taking a field-specific range uncertainty (RU) into account. Dose volume histograms (DVH) were analyzed for PTV2, PTV2 with range uncertainty margin (PTV2RU), rectum, bladder, right/left femoral heads, and penile bulb. For late rectal toxicities, the normal tissue complication probabilities (NTCP) were calculated using different biological models. A DVH- and NTCP-based dosimetric comparison was carried out between non-spacer and spacer groups. Results For the 23 patients, high-quality plans could be achieved for target volume and for other organs at risk (OARs). For PTV2, the V107% was 0% and the Dmax did not exceed 106.2% of the prescribed dose. The volume PTV2RU covered by 95% of the dose ranged from 96.16 to 99.95%. The conformality index for PTV2RU was 1.12 ± 0.057 and the homogeneity index (HI) was 1.04 ± 0.014. Rectum Dmax and rectal volume receiving 73–50 Gy could be further reduced for the spacer-group. Significant reductions in mean and median rectal NTCPs (stenosis/necrosis, late rectal bleeding ≥ 2, and late rectal toxicities ≥ 3) were predicted for the spacer group in comparison to the non-spacer group. Conclusion Hypofractionated/dose escalated radiotherapy with SIB-IMPT is dosimetrically feasible. Further reduction of the rectal volumes receiving high and medium dose levels (73–50 Gy) and rectal NTCP could be achieved through injection of spacers between rectum and prostate.

BACKGROUND: Central nervous system (CNS) germ cell tumours (GCT) comprise a heterogeneous and relatively rare group of neoplasms. Improving the ability to conduct international clinical trials for CNS GCT requires use of homogeneous, common objective disease assessments and standardised response criteria. Currently, different criteria are employed between European and North American protocols for assessing radiological disease response. METHODS: An international working group of the European Society for Paediatric Oncology (SIOPE) Brain Tumour Group (BTG) and North American Children’s Oncology Group (COG) was therefore established to develop consensus recommendations for imaging response assessment for CNS GCT. The working group first reviewed existing literature and current practices and identified major challenges regarding imaging assessment. RESULTS: New clinical imaging standards were defined for the most common sites of intracranial GCT disease (suprasellar/pineal/bifocal), as well as for definition of loco-regional extension. In particular, clear standards were highlighted for definition of partial response (PR) and complete response (CR) to induction chemotherapy at different sites. Furthermore, growing teratoma syndrome (GTS) was clearly defined [apparent radiological increase in non-germinomatous GCT (NGGCT) size during induction chemotherapy despite normalising/normalised AFP/HCG markers – requiring surgery], to avoid such potential cases being classified as progressive disease (PD). CONCLUSION: This consensus will allow more consistent prospective neuroradiological evaluation of response to therapy for patients with CNS GCT and facilitate direct comparison of treatment outcomes across international studies. Ultimately, it may allow international trials to be developed and undertaken across a larger group of collaborating nations, which will be essential to answer many of the remaining questions for this rare but diverse group of tumours.

BACKGROUND: Follow-up examinations are an essential part of the aftercare of patients with brain tumours. We investigated survival in relation to neurological impairment and positive CSF findings at first relapse/progression of medulloblastomas. METHODS: We collected data from patients with relapsed medulloblastoma from the German HIT-REZ studies (HIT-REZ-1997, HIT-REZ-2005, HIT-REZ-Register, n=342). Survival differences dependent on tumour cell-positive and -negative CSF cytology as well as on new onset or worsening of neurological impairment (i.e. headache, nausea/vomiting, ataxia, seizures and others) were analysed. RESULTS: 247 patients with a recurrent medulloblastoma were evaluable for CSF cytology at first relapse/progression (positive n=97, negative n=150). Patients with tumour cell-positive CSF results showed a significantly shorter median PFS and OS time compared to patients with negative CSF cytology [PFS: 9.1 (CI: 5.3-12.9) vs. 16.8 (CI: 13.8-19.8) months, plog rank test=0.001; OS: 14.4 (CI: 12.3-16.4) vs. 41.8 (CI: 33.3–50.4) months, plog rank test

INTRODUCTION: Malignant rhabdoid tumors (MRT) predominantly affect infants. Patients below six months represent a particularly challenging group: intensity of therapy is limited by toxicity to developing organs. Information on prognostic factors, toxicity and long term outcome is sparse. METHODS: Clinical, genetic, and treatment data of 100 patients (less than 6 months at diagnosis) from 13 European countries were analyzed (2005-2020). Tumors and matching blood samples were examined for SMARCB1 mutations using FISH, MLPA and Sanger sequencing. DNA-methylation subgroups (ATRT-TYR, ATRT-SHH, and ATRT-MYC) were determined using DNA methylation arrays. RESULTS: A total of 45 patients presented with ATRT, 29 with extracranial, extrarenal (eMRT) and 9 with renal rhabdoid tumors (RTK). Seventeen patients demonstrated synchronous tumors (SYN). Distant metastases at diagnosis (M+) were present in 27% (26/97). A germline mutation (GLM) was detected in 55% (47/86). Methylation subgroup status was available in 50% (31/62) of ATRT or SYN (SHH=13, TYR=13, MYC=4, SHH+TYR=1). The 5-year overall- (OS) and event free survival (EFS) rates were 23.5±4.6% and 19±4.1%, respectively. Male sex (11±5% vs. 35.8±7.4%), M+ (6.1±5.4% vs. 36.2±7.4%), presence of SYN (7.1±6.9% vs. 26.6±5.3%) and -GLM (7.7±4.2% vs. 45.7±8.6%) were significant prognosticators of 5-year OS, in univariate analysis. Molecular subgroup and survival analyses confirmed the previously described survival advantage of ATRT-TYR. In an adjusted multivariate model clinical factors that influence prognosis were: male sex [HR: 2.1 (1.2 – 3.6)], M+ [3.3 (1.8 – 6)], GLM [HR: 2 (1.1 – 3.6)] and maintenance therapy [HR: 0.3 (0.1 – 0.8)]. CONCLUSION: In this large cohort of homogenously treated infants with MRT, significant predictors of outcome were sex, M+, GLM and maintenance therapy. We confirm the need to stratify which patient group benefits from multimodal treatment, and which patients need novel therapeutic strategies. Biomarker-driven tailored trials may be a key option.

BACKGROUND: Individuals with rhabdoid tumor predisposition syndrome (RTPS1 – SMARCB1, RTPS2 – SMARCA4) have a propensity to develop malignant rhabdoid tumors (MRT). Affected patients typically present < age 12 months with synchronous tumors (SYN) exhibiting an unusually aggressive clinical behavior. Due to the rarity of RTPS, standards for management are evolving. METHODS: Clinical, genetic, and treatment data of 90 patients with RTPS from 16 countries were analyzed (2004 – 2020). Therapy followed the EU-RHAB recommendations. Tumors and matching blood samples were investigated for SMARCB1 and/or SMARCA4 mutations using FISH, MLPA and sequencing. DNA-methylation subgroups were determined using DNA methylation arrays. RESULTS: The median age at diagnosis of 52 girls and 38 boys was 5.5 months (0 – 203). 55.5% (50/90) of patients presented with an atypical teratoid/rhabdoid tumor (ATRT), 23.5% (21/90) demonstrated SYN, and 21% (19/90) extracranial MRT. RTPS1 was present in 84-, RTPS2 in six patients. In 77% (65/84) complete data on SMARCB1 mutational status were generated. Methylation subgroup status was available in 59% (40/68) of ATRT or SYN. The 5-year overall- (OS) and event free survival rates of patients with RTPS1 were 19.8 ± 4.8% and 15 ± 4.2%, respectively. Age < 1 year at diagnosis (10.1±4.3% vs. 46.7±11.1%), presence of SYN (5.3±5.1% vs. 24.8±6%), histological diagnosis (ATRT vs. eMRT/RTK/SYN) (26.8±7.1% vs. 11.9±5.6%), localized disease (34.5±8 vs. 8.3±4.6%), and presence of PGV at C-terminal (33±8.6% vs. 9.4±5.3%) were significant prognostic factors for 5-year OS in univariate analysis. INTERPRETATION: In the largest cohort of patients with RTPS, predictors significant for positive outcome could be detected: age > 1 year, absence of SYN, histological diagnosis ATRT, localized disease and PGV located at C-terminal. In our research project, we aim to characterize the complete pheno- and genotype of patients with RTPS to develop a risk score including surveillance recommendation.

OBJECTIVES: Embryonal tumors with multilayered rosettes (ETMR) are rare malignancies of the central nervous system occurring predominantly in early childhood. Little is known about optimal time point and target volume of radiotherapy for the respective patients. The aim of this analysis was to evaluate treatment outcome in pediatric patients with ETMR treated with Proton Therapy (PT). METHODS: Between May 2016 and August 2021, 15 patients (9 male /6 female) with ETMR received PT in our institution and were enrolled in the prospective registry study KiProReg. Patient characteristics, treatment and outcome according to standardized follow-up data were descriptively analyzed by summarizing frequencies due to small sample size. RESULTS: Median age at PT was 3.0 years (range, 1.6-4.0 years). Three patients presented with metastatic disease (M1 n=1; M2 n=1; M2/3 n=1). Eight patients were treated with salvage PT at tumor progression or recurrence. Residual disease was present in three patients at start of PT. Tumor site was infratentorial (n=3) or supratentorial (n=12). All patients received Chemotherapy (CTX) prior to PT including high dose CTX (n=9) and intrathecal CTX (n=3). Concomitant CTX with temozolomide was administered in one patient. Patients received local PT (n=8) or craniospinal irradiation (CSI) followed by a local boost (n=7). Median dose was 54.0 Gy(RBE) (range, 3.6 -59.4 Gy(RBE)). PT was terminated prematurely in one patient due to cerebral edema and disease progression. Median follow-up after diagnosis was 16.3 months (range, 6.6-65.7 months) and 5.1 months (range, 0-62.4 months) after PT. Four patients treated for salvage experienced disease progression within three months after PT, three of them deceased. CONCLUSION: Preliminary results suggest promising outcomes for childhood ETMR after PT, especially in patients treated at initial diagnosis. Longer follow-up and larger cohorts are desirable to assess long-term survival and necessity of CSI.

BACKGROUND: Proton beam therapy (PBT) compared to photon-based radiotherapy (XRT) offers the benefit to administer lower radiation doses to critical organs thereby possibly minimizing the risk of sequelae in patients with residual craniopharyngiomas (CP) after hypothalamus-sparing surgery. The validation in large CP patient cohorts is still pending. PATIENTS AND METHODS: Of 290 childhood-onset CP patients included 2007-2019 in the prospective multicenter trial KRANIOPHARYNGEOM 2007, 99 (34%) received external RT (65% PBT, 35% XRT). Outcome was compared between the different groups in terms of overall (OS) and event-free survival (EFS), quality of life (QoL using PEDQOL), functional capacity (FMH), and auxological data (BMI and height SDS) one, three and five years after irradiation/CP diagnosis. RESULTS: PBT became the predominant irradiation technique during the study period (used in 23% and 77% of all irradiated patients registered within the first and second half of the enrollment period, respectively). PBT as well as XRT were associated with high (p

11531 Background: In patients with Ewing Sarcoma (EWS), adjuvant radiotherapy is often performed after surgery that could not obtain wide margins or after poor histological response to surgery. However, the benefit of adjuvant radiotherapy needs further investigation. Therefore, we compared event-free survival (EFS) between surgery (SX) alone and SX combined with radiation therapy (RT), performed a subgroup analysis and identified independent prognostic factors. Methods: The data from localized EWS patients with tumors at the extremities that were treated in the Ewing 2008 trial from 2009-2018 were included in this analysis. Patients received induction chemotherapy according to the protocol and then underwent local therapy. Patients receiving SX or adjuvant RT (combined SX/RT) were included in this analysis. Hazard ratios (HRs) (95% Confidence Intervals (CIs)) were calculated using Cox regression. Results: 360 out of 863 patients (41.7%) presented with an EWS at the extremities with 81 tumors at the upper extremity, and 279 tumors at the lower extremity. Most patients were treated with surgery only (223, 61.94%), while 125 patients (34.72%) were treated with SX plus RT. Adjuvant radiotherapy was conducted after a median time of 69 days (1st quartile, 3rd quartile; 54, 109). Median EFS at 5-years for all patients was 0.74 (0.69, 0.80), 0.76 (0.70, 0.83) for patients after surgery only, and 0.73 (0.64, 0.83) after combined RT/SX. After adjusting for sex, age, tumor volume, histological response and surgical margins, the HR for combined RT/SX vs SX alone was 0.69 (0.37, 1.26), p = 0.22. In patients with poor histological response to surgery (≥10% vital tumor cells) and with high tumor volume (≥ 200mL), additional radiotherapy did not decrease the hazards of any event, HR 0.72 (0.25, 2.06), p = 0.54. We identified high tumor volume, poor histological response to surgery as well as intralesional resection of the tumor as independent prognostic factors after adjusting for other known prognostic factors with HRs of 1.73 (1.04, 2.90), p = 0.03; 2.79 (1.69, 4.62), p < 0.0001 and 215.9 (13.17, 3538.61), p = 0.0002, respectively. Surgical complication was not a prognostic factor after adjusting for above mentioned variables, HR 0.85 (0.31, 2.34), p = 0.75. Conclusions: In our cohort, adjuvant radiotherapy was not superior compared to surgery alone in all patients with localized EWS at the extremities and neither in a subgroup of patients with high-risk factors. Poor histological response, intralesional tumor resection as well as high tumor volume were identified as independent negative prognostic factors. Clinical trial information: NCT00987636.

BACKGROUND: Proton therapy (PT) is a valuable alternative to photon radiotherapy in treatment of CNS tumors in children and adolescents. The aim of this study was to investigate the feasibility of recent treatment strategies with a particular focus on the acute toxicity of a simultaneous radiotherapy and chemotherapy (sRCT). PATIENTS AND METHODS: We investigated 199 patients (116 male, 83 female, median age 7.4 years) who received in total 200 cycles of PT (60.5% at new diagnosis, 39.5% at relapse) from September 2013 to February 2017. Entities included ependymomas (34%), medulloblastomas (16%), low grade gliomas (13%), ATRTs (12%), craniopharyngiomas (9%), germ cell tumors (6%), and other entities (10%). SRCT was administered in 52 (26%) treatment cycles. The target tumor was predominantly localized infratentorial (53%), supratentorial (23.5%) and supra-/intrasellar (18%). 38 patients received additional CSI and 8 patients a boost to metastases. Data were collected retrospectively based on patient records. Toxicity was documented according to CTCAE version 4.03. RESULTS: Severe adverse events (SAE ≥ grade 3) occurred in 33.5% of all patients, in particular in form of hematotoxicity (64.1%) and infections (26.8%). In-patient treatment for unexpected SAEs was necessary in 33 patients (16.5%). In the group treated with sRCT 15 out of 52 (28.8%) patients couldn’t receive the recommended dose or time schedule of planned chemotherapy due to SAEs. Comparing the SAE frequency in both groups, the children who have been treated with sRCT had a significantly higher risk of SAEs than the patients who have received proton therapy only (63.5% vs. 23.0%, p=0.001). CONCLUSIONS: PT and concomitant chemotherapy are feasible, but require an interdisciplinary team with continuous out-/inpatient management of patients, as the risk of toxicity is significantly increased. Risk-adapted adjustment of simultaneous chemotherapy is necessary to reduce relevant interruptions of radiotherapy. Funded by the German Childhood Cancer Foundation

Objective: Radiotherapy (RT) is an integral part of the interdisciplinary treatment of patients with high-risk neuroblastoma (NB). With the continuous improvements of outcome, the interest in local treatment strategies that reduce treatment-related side effects while achieving optimal oncological results is growing. Proton beam therapy (PBT) represents a promising alternative to conventional photon irradiation with regard to the reduction of treatment burden. Method: Retrospective analysis of children with high or intermediate risk NB receiving PBT of the primary tumor site during first-line therapy between 2015 and 2020 was performed. Data from the prospective in-house registry Standard Protonentherapie WPE – Kinder- (KiProReg) with respect to tumor control and treatment toxicity were analyzed. Adverse events were classified according to CTCAE Version 4 (V4.0) before, during, and after PBT. Results: In total, 44 patients (24 male, 20 female) with high (n = 39) or intermediate risk NB (n = 5) were included in the analysis. Median age was 3.4 years (range, 1.4–9.9 years). PBT doses ranged from 21.0 to 39.6 Gray (Gy) (median 36.0 Gy). Five patients received PBT to the MIBG-avid residual at the primary tumor site at time of PBT according to the NB-2004 protocol. In 39 patients radiation was given to the pre-operative tumor bed with or without an additional boost in case of residual tumor. After a median follow-up (FU) of 27.6 months, eight patients developed progression, either local recurrence (n = 1) or distant metastases (n = 7). Four patients died due to tumor progression. At three years, the estimated local control, distant metastatic free survival, progression free survival, and overall survival was 97.7, 84.1, 81.8, and 90.9%, respectively. During radiation, seven patients experienced higher-grade (CTCAE ≥ °3) hematologic toxicity. No other higher grade acute toxicity occurred. After PBT, one patient developed transient myelitis while receiving immunotherapy. No higher grade long-term toxicity was observed up to date. Conclusion: PBT was a well tolerated and effective local treatment in children with high and intermediate risk NB. The role of RT in an intensive multidisciplinary treatment regimen remains to be studied in the future in order to better define timing, doses, target volumes, and general need for RT in a particularly sensitive cohort of patients. OA Förderung 2021

PURPOSE: To create a digital, online atlas for organs at risk (OAR) delineation in neuro-oncology based on high-quality computed tomography (CT) and magnetic resonance (MR) imaging. METHODS: CT and 3 Tesla (3T) MR images (slice thickness 1 mm with intravenous contrast agent) were obtained from the same patient and subsequently fused. In addition, a 7T MR without intravenous contrast agent was obtained from a healthy volunteer. Based on discussion between experienced radiation oncologists, the clinically relevant organs at risk (OARs) to be included in the atlas for neuro-oncology were determined, excluding typical head and neck OARs previously published. The draft atlas was delineated by a senior radiation oncologist, 2 residents in radiation oncology, and a senior neuro-radiologist incorporating relevant available literature. The proposed atlas was then critically reviewed and discussed by European radiation oncologists until consensus was reached. RESULTS: The online atlas includes one CT-scan at two different window settings and one MR scan (3T) showing the OARs in axial, coronal and sagittal view. This manuscript presents the three-dimensional descriptions of the fifteen consensus OARs for neuro-oncology. Among these is a new OAR relevant for neuro-cognition, the posterior cerebellum (illustrated on 7T MR images). CONCLUSION: In order to decrease inter- and intra-observer variability in delineating OARs relevant for neuro-oncology and thus derive consistent dosimetric data, we propose this atlas to be used in photon and particle therapy. The atlas is available online at www.cancerdata.org and will be updated whenever required. ispartof: RADIOTHERAPY AND ONCOLOGY vol:128 issue:1 pages:37-43 ispartof: location:Ireland status: published