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INTRODUCTION:The H3K27M-mutant diffuse midline glioma (DMG) was first included in the World Health Organization (WHO) Classification of central nervous system (CNS) tumors in 2016, and confirmed in its fifth edition. The biological behavior and dismal prognosis of this tumor resemble diffuse intrinsic pontine gliomas (DIPG). Homogeneously-treated series are rarely reported.METHODS:From 2016 onwards, we treated patients with DMG with radiotherapy and concomitant/adjuvant nimotuzumab/vinorelbine, plus re-irradiation at relapse, as already done for DIPG.RESULTS:We treated nine patients, seven females, with a median age at diagnosis of 13 years. Tumor sites were: thalamic in five cases, pontocerebellar in two, pineal in one, and paratrigonal with nodular/leptomeningeal dissemination in one. Three patients were biopsied, and six had partial tumor resections. Central pathological review was always performed. The median time to local progression was 12.7 months, and the median overall survival was 17.8 months. Six patients died of tumor progression, one of cerebral bleeding at progression. Two were alive, one in continuous remission, the other after relapsing, at 38.6 and 46.3 months after diagnosis. Progression-free survival was 33.3% at one year. Overall survival was 88.9%, 33.3% and 22.2% at 1, 2 and 3 years, respectively.CONCLUSIONS:This is a small series of homogeneously-treated DMG patients. The results obtained are comparable with those of DIPG patients. Given the phenotypically- and molecularly-defined setting of DMG and severe outcome in this orphan population, they should be treated and included in registries and protocols of DIPG.

Abstract Objective To report on a retrospective study of primary DSRCT aiming at characterizing long‐term survivors (LTS). Methods All consecutive patients treated at our institution for a primary DSRCT between 2000 and 2021 were retrospectively identified. Patients received multiagent chemotherapy ± surgery ± hyperthermic intraperitoneal chemotherapy (HIPEC) ± whole abdomino‐pelvic radiotherapy (WAP‐RT) ± high‐dose chemotherapy ± maintenance chemotherapy (MC). Event‐free survival (EFS) and overall survival (OS) were estimated by Kaplan–Meier method. Patients alive, without evidence of disease at ≥36 months from diagnosis, were defined as LTS. Results Thirty‐eight patients were identified. All received multiagent chemotherapy; 27/38 (71%) surgery (7/27 [26%] plus HIPEC), 9/38 (24%) WAP‐RT, 12/38 (32%) MC. At a median‐follow‐up of 37 months (IQR 18–63), overall median‐EFS and median‐OS were 15 and 37 months, respectively. All events occurred within 35 months. In patients who underwent surgery, median‐EFS and median‐OS were 19 and 37 months (23 and 43 months after R0/R1, and 10 and 19 months after R2 resection), respectively. LTS were 5/38 (13%), alive at 37, 39, 53, 64, 209 months. None had liver or extra‐abdominal metastasis at diagnosis, they all received R0/R1 resection, 3/5 had WAP‐RT, 2/5 MC, 1/5 received high‐dose chemotherapy, none HIPEC. Conclusions In our series cure was likely achieved in 13% of DSRCT. LTS had no liver/extra‐abdominal disease, were treated with complete surgery, and possibly WAP‐RT/MC.

Abstract Enrolling medulloblastoma(MB) patients in the PNET5 protocol is a daily problem in Italy; since June 2015, 59 cases have been enrolled in 13 centres. So far, 44 of the 103 patients claiming for eligibility did not enter the protocol: 13 metastases, 5 for residual, 20 having exclusion criteria, 4 insufficient frozen material, 2 failure to comply with the correct procedures. No case was lost due to delayed centralization, which is respected even with committing weekends; review of the radiation plan was performed on Saturday for 2 cases, and radiotherapy began on the same day. We made some procedural changes to meet expected deadlines; each local centre notifies the national coordinator of a possible case's existence at MRI diagnosis, of the expected surgery date as well as its realization. MRI imaging is reviewed within 2 days after centralization. Paediatricians notify the national coordinator and pathology/biology reference centre of the MB diagnosis; the shipment of frozen tissue, blood and FFPE is booked. A slot is reserved to priority perform the central pathology review, as well as central molecular diagnosis of genetically defined subgroup (WHO classification) upon receipt of the frozen material. Upon receipt of the FFPE and frozen material, the national reference centre undertakes a double-check with the national coordinator and the local treatment centre to validate the eligibility. Within the 7th day from the receipt of the material: IHC, MYC/MYCN, Monosomy 6, beta-catenin mutation and methylation array are performed. Priority execution of somatic (blood control) sequencing of the PTCH, SUFU, and TP53 genes is also triggered for SHH-activated MB, with the deadline on the 15th day. So far we have had 99% agreement between molecular subgrouping and methylation array. CONCLUSIONS: PNET5 requirements are multiple and changing over time; difficulties may and must be overcome by mutual fast collaboration.

The prognosis for patients with metastatic rhabdomyosarcoma (RMS) remains largely unsatisfactory despite the adoption of intensive multimodal therapy. To assess the role of different treatments adopted over the years, we retrospectively analyzed a cohort of patients <21 years old with metastatic RMS, treated from 1990 to 2020 at a referral center for pediatric sarcomas.

(1) Background: The relationship between processing speed (PS) and psychological adjustment in the healthy population is well established, as is that between low socio-economic status (SES) and psychological distress. While PS is one of the most impaired functions in pediatric brain tumor survivors (PBTSs), previous research has demonstrated that low SES may be a predictor of increased psychosocial risk in PBTSs. Given the psychological adjustment difficulties observed in PBTS, in the current study we aimed to explore the relationship between SES and psychological functioning, considering the contribution of PS as a mediator. (2) Methods: demographic and clinical data of 80 children (age range: 4–17 y.o.) were retrospectively collected. Psychological measures were the parent-compiled versions of the Child Behavioral Checklist (CBCL) and the Strengths and Difficulties Questionnaire (SDQ). Mediation analysis models were performed on psychological measures with and without the inclusion of covariates. (3) Results: The influence of SES on the CBCL total index was mediated by PS. Furthermore, PS was found to have a mediating effect on the relationship between SES and internalizing problems but not on the relationship between SES and externalizing problems. (4) Conclusions: The results suggest that PS may be a rehabilitation target for the prevention of psychological distress and should be addressed especially for PBTSs who live in a disadvantaged situation.

Purpose The aim of this study is to investigate the spectrum of neurological triad improvement in patients with diffuse intrinsic pontine glioma (DIPG) treated by re-irradiation (re-RT) at first progression. Methods We carried out a re-analysis of the SIOP-E retrospective DIPG cohort by investigating the clinical benefits after re-RT with a focus on the neurological triad (cranial nerve deficits, ataxia, and long tract signs). Patients were categorized as “responding” or “non-responding” to re-RT. To assess the interdependence between patients’ characteristics and clinical benefits, we used a chi-square or Fisher’s exact test. Survival according to clinical response to re-RT was calculated by the Kaplan–Meier method. Results As earlier reported, 77% ( n = 24/31) of patients had any clinical benefit after re-RT. Among 25/31 well-documented patients, 44% ( n = 11/25) had improvement in cranial nerve palsies, 40% ( n = 10/25) had improvement in long-tract signs, and 44% (11/25) had improvement in cerebellar signs. Clinical benefits were observed in at least 1, 2, or 3 out of 3 symptoms of the DIPG triad, in 64%, 40%, and 24%, respectively. Patients irradiated with a dose ≥20 Gy versus <20 Gy may improve slightly better with regard to ataxia (67% versus 23%; p -value = 0.028). The survival from the start of re-RT to death was not different between responding and non-responding DIPG patients ( p -value = 0.871). Conclusion A median re-irradiation dose of 20 Gy provides a neurological benefit in two-thirds of patients with an improvement of at least one symptom of the triad. DIPG patients receiving ≥20 Gy appear to improve slightly better with regard to ataxia; however, we need more data to determine whether dose escalation up to 30 Gy provides additional benefits.

Abstract BACKGROUND: The purposes of this trial were to evaluate the feasibility, response, PFS/OS of a randomized study comparing two different RT schedules for DIPG while administering the same systemic treatment. METHODS: Patients: 2-21 years-old with a not-pretreated radiologically verified DIPG (MRI blindly reviewed at diagnosis and every 12 weeks thereafter) and symptoms duration below 6 months. Biopsy was required if suggested by atypical imaging. Vinorelbine 20 mg/m2+nimotuzumab 150 mg/m2 were administered weekly for 12 weeks; thereafter every other week until tumor progression or for up to 2 years. Standard(ST) arm included focal RT at total dose of 54Gy (1.8Gy/day); for local progression re-irradiation was proposed at 19.8Gy, in case of dissemination craniospinal irradiation(CSI) at 36Gy was adopted. Experimental(SP) arm included three elective courses of RT at defined timepoints at 36Gy, 19.8Gy and 19.8Gy with possible reirradiation for relapse at 9 Gy. Incidences of local(L) and distant(D) progression were assessed in a competing risk setting. RESULTS: Aggregated preliminary results are given for 4 Italian centers. 54 pts were screened and 51 included, 27 in ST, 28 males, median age 7 years (range 3-17). Median time of observation was 17.9 months. Twelve patients needed a shunt, 10 during treatment; 20 were biopsied, in 18 cases according local protocols. 19/20 tumors had H3.3 K27 mutation. 41 relapsed, 28 locally, 13 with a component of dissemination. 36 died, one for tracheotomy bleeding. SP irradiation was feasible and never produced significant radionecrosis. Median EFS/OS were 7.3/12.9 months, respectively; EFS/OS at 1 year were 19.0%/57.3%, not differing between patients with local vs. disseminated relapses. Patients submitted to biopsies had more dissemination (P=0.04) and less local progression (P=0.077). CONCLUSIONS: Treatment was feasible and OS confirmed previous results obtained in a single center. Randomization results will be later reported.

Background:The clinical management of ependymoma in childhood and adolescence is complex and the clinicobiopathological correlates of outcome remain poorly understood. This international SIOP Ependymoma II (SIOP EPII) trial aims to improve the outcome of patients with ependymoma.MethodsSIOP EPII includes any patient <22 years at diagnosis with ependymoma, stratified by age, tumor location, and outcome of the initial surgery. Centralized pathology and imaging is required for diagnosis confirmation. SIOP EPII included three randomized studies according to age, postoperative residue, and suitability to receive radiotherapy. Patients ineligible for interventional strata are followed-up in an observational study. The staging phase aims to determine if central neurosurgical and radiological postoperative MRI reviews increase the resection rate. Patients ≥12 months with (i) no residual disease are randomly assigned in a phase III trial to evaluate the efficacy of post-radiation 16-week chemotherapy (VEC + CDDP) on PFS (stratum I); (ii) centrally confirmed measurable inoperable residual disease are allocated to randomized frontline chemotherapy phase II study (VEC vs. VEC + high-dose methotrexate) and considered for a second-look surgery (stratum II). If second-look surgery is not feasible or tumor residuum remains, patients receive 8 Gy-boost radiotherapy after conformal radiotherapy (phase I). (iii) Patients < 12 months (18 months in the UK) or not eligible to receive radiotherapy are randomized in a phase II study to receive chemotherapy (alternated myelosuppressive and nonmyelosuppressive chemotherapy), with or without valproate (stratum III). To overcome the limitations encountered in the preliminary conclusions of the ACNS-0831 study, a SIOP EPII dedicated on-study amendment has been planned to definitively conclude the relevance of maintenance chemotherapy in stratum I. Secondary outcomes include overall survival, quality of life, neuropsychological and neuroendocrine outcomes, safety, and identification of key prognostic biomarkers (BIOMECA).Clinical Trial RegistrationClinicalTrials.gov, identifier: NCT02265770.

Abstract BACKGROUND: Incidence of iatrogenic pulmonary toxicity is around 20%. Apart from bleomycin fibrosis, the role of lomustine, HD-thiotepa, autologous stem-cells transplantation(APBSCT) and their synergy with craniospinal irradiation(CSI) are unclear. To elucidate their role in lung-function impairment, we retrospectively evaluated 39 medulloblastoma patients treated at INT-Milan and OPBG-Rome. METHODS: 39 patients (17 females, median RT age 8 years) treated for localized(29) or metastatic(10) medulloblastoma in 2000-2020 and with spirometric assessment, were considered. Treatment included: SIOP-like-PNET IV(19), high-risk protocol(19), infant protocol without RT(1). CSI doses were: 23.4Gy(20), 31.2Gy(8), 36Gy(6) and 39Gy(4); 4 received protons and 34 photons(9 VMAT, 25 3D), 11 hyperfractionated-accelerated-RT; 33 had 6 median CCNU cycles; 6 APBSCT. RESULTS: Median follow-up: 98 months. All patients performed at least one spirometry at median 5 years after RT. Eight (20.6%) had mildly pathological spirometries, 8 Forced Vital Capacity (FVC%)<90%. RT age was not associated with FVC%/ PEF% (p=0.319 and 0.405). A lower Peak Expiratory Flow(PEF%) was marginally associated to APBSCT group (p=0.062) with FVC%(≤90% vs >90%) similar but less significant(p=0.163). Median FVC%/PEF% were higher in the CCNU-group without reaching significance (p=0.436 and 0.062): this was a standard-risk group not receiving APBSCT nor higher RT doses. Even though the lung volume encompassed by 5-10 Gy isodoses was greater in VMATvs3D RT(p<0.001 and p=0.015), there were no significant differences in ventilatory parameters. FVC%/PEF% were negatively associated to CSI dose. Since no relevant lung volume is involved in high doses, a multifactorial etiology could be speculated. CONCLUSIONS: Preliminary data show no significant FVC%/PEF% reduction. Small sample size and differences in spirometry techniques impose larger cohorts accrual to elucidate potential treatment-induced pulmonary impairment in the pediatric population thus validating the use of spirometry during treatment/follow-up.

Diffuse midline gliomas (DMGs) originate in the thalamus, brainstem, cerebellum and spine. This entity includes tumors that infiltrate the pons, called diffuse intrinsic pontine gliomas (DIPGs), with a rapid onset and devastating neurological symptoms. Since surgical removal in DIPGs is not feasible, the purpose of this study was to profile circulating miRNA expression in DIPG patients in an effort to identify a non-invasive prognostic signature with clinical impact. Using a high-throughput platform, miRNA expression was profiled in serum samples collected at the time of MRI diagnosis and prior to radiation and/or systemic therapy from 47 patients enrolled in clinical studies, combining nimotuzumab and vinorelbine with concomitant radiation. With progression-free survival as the primary endpoint, a semi-supervised learning approach was used to identify a signature that was also tested taking overall survival as the clinical endpoint. A signature comprising 13 circulating miRNAs was identified in the training set (n = 23) as being able to stratify patients by risk of disease progression (log-rank p = 0.00014; HR = 7.99, 95% CI 2.38–26.87). When challenged in a separate validation set (n = 24), it confirmed its ability to predict progression (log-rank p = 0.00026; HR = 5.51, 95% CI 2.03–14.9). The value of our signature was also confirmed when overall survival was considered (log-rank p = 0.0021, HR = 4.12, 95% CI 1.57–10.8). We have identified and validated a prognostic marker based on the expression of 13 circulating miRNAs that can shed light on a patient’s risk of progression. This is the first demonstration of the usefulness of nucleic acids circulating in the blood as powerful, easy-to-assay molecular markers of disease status in DIPG. This study provides Class II evidence that a signature based on 13 circulating miRNAs is associated with the risk of disease progression.

Abstract AIMS: We report a cohort of YCMB cases homogeneously treated with HDCT in two Italian institutions, and the prognostic impact of histology and genetics retrospectively evaluated. METHODS: All YCMB (aged≤3 years) treated with upfront HDCT in the period 1998-2019 were included, reclassified according to the WHO2021 classification of CNS tumours. Mutational status ofPTCH1, SUFU, and TP53 was analysed in selected cases. Histology and genetics were correlated with survival, secondary tumours(STs), and cancer predisposition syndromes(CPSs). RESULTS: Fifty-three patients were enrolled (62.3% male), median age 2.2 years. 21 had classic(CMB), 15 desmoplastic/nodular(DMB), 11 MBEN and 6 large-cell/anaplastic(AMB/LCMB) medulloblastoma. Metastases were present in 18. Genomic pattern showed SHH-TP53wt in 29 cases, non-WNT/non-SHH in 22; 2 were SHH-TP53mut. Induction chemotherapy (VCR/HDMTX, HDVP16, VCR/HDCTX and HDCARBO) was followed by 2-3 HDCT courses; irradiation reserved to cases with metastatic disease and/or residual tumours. 22 patients never received irradiation. SHH-TP53wt cases had significantly less metastasis (p=0.002), while non-WNT/non-SHH received more often irradiation (p<0.0001). OS at 5, 10, and 20 yrs was 0.73, 0.70 and 0.57 respectively in the entire cohort; stable at 0.85 (at 5, 10, and 20 yrs) in SHH-TP53wt patients while 0.58, 0.51 and 0.17 in the non-WNT/non-SHH. PFS at 5, 10, 20 yrs was stable at 0.89 in SHH-TP53wt and remained 0.35 in non-WNT/non-SHH. 13/53 patients presented Gorlin Syndrome; 1 had familial MB. 16 STs were reported in 14 cases; life-threatening, irradiation-related STs mainly in non-WNT/non-SHH cases. In SHH-TP53wt benign tumours or related to CPS were reported. CONCLUSIONS: This is one of the first series of YCMB treated with HDCT without stratification for stage and histology. The long follow-up highlights the frequency/types of associated CPS and STs; the latter, in non-WNT/non-SHH, were treatment-related and life-threatening.

BACKGROUND:More than 40% of patients with intracranial ependymoma need a salvage treatment within 5 years after diagnosis, and no standard treatment is available as yet. We report the outcome after first relapse of 64 patients treated within the 2nd AIEOP protocol. METHODS:We considered relapse sites and treatments, that is, various combinations of complete/incomplete surgery, if followed by standard or hypofractionated radiotherapy (RT) ± chemotherapy (CT). Molecular analyses were available for 38/64 samples obtained at first diagnosis. Of the 64 cases, 55 were suitable for subsequent analyses. RESULTS:The median follow-up was 147 months after diagnosis, 84 months after first relapse, 5-year EFS/OS were 26.2%/30.8% (median EFS/OS 13/32 months) after relapse. For patients with a local relapse (LR), the 5-year cumulative incidence of second LRs was 51.6%, with a 5-year event-specific probability of being LR-free of 40.0%. Tumor site/grade, need for shunting, age above/below 3 years, molecular subgroup at diagnosis, had no influence on outcomes. Due to variation in the RT dose/fractionation used and the subgroup sizes, it was not possible to assess the impact of the different RT modalities. Multivariable analyses identified completion of surgery, the absence of symptoms at relapse, and female sex as prognostically favorable. Tumors with a 1q gain carried a higher cumulative incidence of dissemination after first relapse. CONCLUSIONS:Survival after recurrence was significantly influenced by symptoms and completeness of surgery. Only a homogeneous protocol with well-posed, randomized questions could clarify the numerous issues, orient salvage treatment, and ameliorate prognosis for this group of patients.

Medulloblastoma patients receive adapted therapies stratified according to their risk-profile. Favourable, standard, and high disease-risk groups are each defined by the status of clinical and pathological risk factors, alongside an evolving repertoire of diagnostic and prognostic biomarkers. Medulloblastoma clinical trials in Europe are coordinated by the International Society for Paediatric Oncology (SIOP-Europe) brain tumour group. Favourable and standard-risk patients are eligible for the SIOP-PNET5-MB clinical trial protocol. In contrast, therapies for high-risk disease worldwide have, to date, encompassed a range of different treatment philosophies, with no clear consensus on approach. Higher radiotherapy doses are typically deployed, delivered either conventionally or in hyper-fractionated/accelerated regimens. Similarly, both standard and high-dose chemotherapies were assessed. However, trials to date in high-risk medulloblastoma have commonly been institutional or national, based on modest cohort sizes, and have not evaluated the relative performance of different strategies in a randomised fashion. We describe the concepts and design of the SIOP-E high-risk medulloblastoma clinical trial (SIOP-HR-MB), the first international biomarker-driven, randomised, clinical trial for high-risk medulloblastoma. SIOP-HR-MB is programmed to recruit >800 patients in 16 countries across Europe; its primary objectives are to assess the relative efficacies of the alternative established regimens. The HR-MB patient population is molecularly and clinically defined, and upfront assessments incorporate a standardised central review of molecular pathology, radiology, and radiotherapy quality assurance. Secondary objectives include the assessment of (i) novel therapies within an upfront ‘window’ and (ii) therapy-associated neuropsychology, toxicity, and late effects, alongside (iii) the collection of materials for comprehensive integrated studies of biological determinants within the SIOP-HR-MB cohort.

BACKGROUND: The purposes of this trial were evaluating the feasibility, response and PFS/OS of patients receiving upfront radiotherapy and reirradiation at progression with concomitant nimotuzumab/vinorelbine chemotherapy as the standard arm of the ongoing protocol for DIPG. METHODS: Patients aged 2-21 years with not-pretreated DMG (evidence of H3.3K27M mutation at immunohistochemistry) received vinorelbine 20 mg/m2+nimotuzumab 150 mg/m2 weekly for 12 weeks; thereafter every other week until tumor progression or for up to 2 years. Focal photons irradiation was delivered within the 3rd week after first nimotuzumab+vinorelbine administration with a total dose of 54 Gy in 1.8 Gy daily fractions. For local progression re-irradiation was proposed at 19.8 Gy; in case of dissemination craniospinal-irradiation at 36 Gy was adopted. MRI were blindly centrally reviewed at diagnosis and every 12 weeks thereafter. RESULTS: Aggregated preliminary results are available for 20 patients from 4 Italian centers: 12 males, median age 11 years (range 3-17). Median time of observation was 12.5 months; 8 had thalamic/basal ganglia disease, in 5 pons was involved (2 pontobulbar, 3 pontomesencephalic), 6 spinal, 2 cerebellar. 13 patients had only biopsy, the others partial or near-total resection.14 relapsed: 5 locally, 4 with dissemination, 5 with both; 12 died, one was lost at follow-up. Two patients received reirradiation, one of them was irradiated three times without evidence of radionecrosis, still alive at 26 months from diagnosis. Median EFS/OS were 8.3/10.2 months, respectively; EFS/OS at 1 year were 25.8/36.7%. Survival curves between spinal and cerebral locations showed no difference. Patients after partial/near-total resection vs biopsied seemed to have earlier relapses (P 0.017) with EFS at 6 months of 34.3/75.0% respectively. CONCLUSIONS: This is one of the first series of DMG homogeneously and prospectively treated; treatment was feasible. A potential role of reirradiation emerge as in DIPGs.

(1) Background: Brain tumor (BT) survivors show difficulties in the acquisition of developmental milestones, related to academic achievement, vocational employment, social relationships, and autonomy. The skills underlying adaptive functioning (AF) are usually damaged in BT survivors due to the presence of the brain tumor, treatment-related factors, and other neurological sequelae. In this study, we aimed to explore the contribution of different cognitive factors in children with BT to AF, considering diagnosis-related variables. (2) Methods: Standardized cognitive assessment was undertaken and clinical information was collected from a retrospective cohort of 78 children with a BT, aged between 6 and 18 year old at the time of the assessment. Regression models were computed to investigate the influence of the selected variables on daily functional skills as measured by the Functional Independence Measure for Children (WeeFIM). (3) Results: The analyses showed that the main explanatory variables are processing speed and time since diagnosis. Other clinical variables, such as age at diagnosis and hydrocephalus, differentially influence functional skills according to distinct domains (i.e., self-care, mobility, and cognition). (4) Conclusions: The main explanatory variables of AF that emerged in our models point to a potential target of improving AF management in pediatric BT survivors.

PURPOSE/OBJECTIVE:About 20% of children with solid tumours (ST) present with distant metastases (DM). Evidence regarding the use of radical radiotherapy of these DM is sparse and open for personal interpretation. The aim of this survey was to review European protocols and to map current practice regarding the irradiation of DM across SIOPE-affiliated countries. MATERIALS/METHODS:Radiotherapy guidelines for metastatic sites (bone, brain, distant lymph nodes, lung and liver) in eight European protocols for rhabdomyosarcoma, non-rhabdomyosarcoma soft-tissue sarcoma, Ewing sarcoma, neuroblastoma and renal tumours were reviewed. SIOPE centres irradiating ≥50 children annually were invited to participate in an online survey. RESULTS:Radiotherapy to at least one metastatic site was recommended in all protocols, except for high-risk neuroblastoma. Per protocol, dose prescription varied per site, and information on delineation and treatment planning/delivery was generally missing. Between July and September 2019, 20/27 centres completed the survey. Around 14% of patients were deemed to have DM from ST at diagnosis, of which half were treated with curative intent. A clear cut-off for a maximum number of DM was not used in half of the centres. Regardless of the tumour type and site, conventional radiotherapy regimens were most commonly used to treat DM. When stereotactic radiotherapy was used, a wide range of fractionation regimens were applied. CONCLUSION:Current radiotherapy guidelines for DM do not allow a consistent approach in a multicentre setting. Prospective (randomised) trials are needed to define the role of radical irradiation of DM from paediatric ST.