Brachytherapy for rhabdomyosarcoma: Survey of international clinical practice and development of guidelines.

BACKGROUND AND PURPOSE: The purpose of this study was to address the lack of published data on the use of brachytherapy in pediatric rhabdomyosarcoma by describing current practice as starting point to develop consensus guidelines. MATERIALS AND METHODS: An international expert panel on the treatment of pediatric rhabdomyosarcoma comprising 24 (pediatric) radiation oncologists, brachytherapists and pediatric surgeons met for a Brachytherapy Workshop hosted by the European paediatric Soft tissue Sarcoma Study Group (EpSSG). The panel's clinical experience, the results of a previously distributed questionnaire, and a review of the literature were presented. RESULTS: The survey indicated the most common use of brachytherapy to be in combination with tumor resection, followed by brachytherapy as sole local therapy modality. HDR was increasingly deployed in pediatric practice, especially for genitourinary sites. Brachytherapy planning was mostly by 3D imaging based on CT. Recommendations for patient selection, treatment requirements, implant technique, delineation, dose prescription, dose reporting and clinical management were defined. CONCLUSIONS: Consensus guidelines for the use of brachytherapy in pediatric rhabdomyosarcoma have been developed through multicenter collaboration establishing the basis for future work. These have been adopted for the open EpSSG overarching study for children and adults with Frontline and Relapsed RhabdoMyoSarcoma (FaR-RMS).

Novel therapeutic approaches for pediatric diencephalic tumors: improving functional outcomes.

Pediatric diencephalic tumors represent a histopathologically and molecularly diverse group of neoplasms arising in the central part of the brain and involving eloquent structures, including the hypothalamic-pituitary axis (HPA), optic pathway, thalamus, and pineal gland. Presenting symptoms can include significant neurological, endocrine, or visual manifestations which may be exacerbated by injudicious intervention. Upfront multidisciplinary assessment and coordinated management is crucial from the outset to ensure best short- and long-term functional outcomes. In this review we discuss the clinical and pathological features of the neoplastic entities arising in this location, and their management. We emphasize a clear move towards 'function preserving' diagnostic and therapeutic approaches with novel toxicity-sparing strategies, including targeted therapies.

Quantitative diffusion-weighted MRI response assessment in rhabdomyosarcoma: an international retrospective study on behalf of the European paediatric Soft tissue sarcoma Study Group Imaging Committee.

OBJECTIVE: To investigate the feasibility of diffusion-weighted magnetic resonance imaging (DW-MRI) as a predictive imaging marker after neoadjuvant chemotherapy in patients with rhabdomyosarcoma. MATERIAL AND METHODS: We performed a multicenter retrospective study including pediatric, adolescent and young adult patients with rhabdomyosarcoma, Intergroup Rhabdomyosarcoma Study group III/IV, treated according to the European paediatric Soft tissue sarcoma Study Group (EpSSG) RMS2005 or MTS2008 studies. DW-MRI was performed according to institutional protocols. We performed two-dimensional single-slice tumor delineation. Areas of necrosis or hemorrhage were delineated to be excluded in the primary analysis. Mean, median and 5th and 95th apparent diffusion coefficient (ADC) were extracted. RESULTS: Of 134 included patients, 82 had measurable tumor at diagnosis and response and DW-MRI scans of adequate quality and were included in the analysis. Technical heterogeneity in scan acquisition protocols and scanners was observed. Mean ADC at diagnosis was 1.1 (95% confidence interval [CI]: 1.1-1.2) (all ADC expressed in * 10-3 mm2/s), versus 1.6 (1.5-1.6) at response assessment. The 5th percentile ADC was 0.8 (0.7-0.9) at diagnosis and 1.1 (1.0-1.2) at response. Absolute change in mean ADC after neoadjuvant chemotherapy was 0.4 (0.3-0.5). Exploratory analyses for association between ADC and clinical parameters showed a significant difference in mean ADC at diagnosis for alveolar versus embryonal histology. Landmark analysis at nine weeks after the date of diagnosis showed no significant association (hazard ratio 1.3 [0.6-3.2]) between the mean ADC change and event-free survival. CONCLUSION: A significant change in the 5th percentile and the mean ADC after chemotherapy was observed. Strong heterogeneity was identified in DW-MRI acquisition protocols between centers and in individual patients.

Management of the vertebrae as an organ at risk in paediatric radiotherapy clinical trials: Initial QUARTET experience.

Irradiation of the vertebrae in prepubertal patients, if non-homogenous, can result in future growth deformities including kyphoscoliosis. Vertebral delineation and dosimetry were assessed for 101 paediatric cases reviewed within QUARTET-affiliated trials. Despite the availability of published consensus guidelines, a high variability in vertebral delineation was observed, with impact on dosimetry.

Shedding a Light on the Challenges of Adolescents and Young Adults with Rhabdomyosarcoma.

Rhabdomyosarcoma (RMS) is a typical tumour of childhood but can occur at any age. Several studies have reported that adolescent and young adult (AYA) patients with RMS have poorer survival than do younger patients. This review discusses the specific challenges in AYA patients with pediatric-type RMS, exploring possible underlying factors which may influence different outcomes. Reasons for AYA survival gap are likely multifactorial, and might be related to differences in tumor biology and intrinsic aggressiveness, or differences in clinical management (that could include patient referral patterns, time to diagnosis, enrolment into clinical trials, the adequacy and intensity of treatment), as well as patient factors (including physiology and comorbidity that may influence treatment tolerability, drug pharmacokinetics and efficacy). However, improved survival has been reported in the most recent studies for AYA patients treated on pediatric RMS protocols. Different strategies may help to further improve outcome, such as supporting trans-age academic societies and national/international collaborations; developing specific clinical trials without upper age limit; defining integrated and comprehensive approach to AYA patients, including the genomic aspects; establishing multidisciplinary tumor boards with involvement of both pediatric and adult oncologists to discuss all pediatric-type RMS patients; developing dedicated projects with specific treatment recommendations and registry/database.

QUARTET: A SIOP Europe project for quality and excellence in radiotherapy and imaging for children and adolescents with cancer.

The European Society for Paediatric Oncology (SIOPE) Radiation Oncology Working Group presents the QUARTET Project: a centralised quality assurance programme designed to standardise care and improve the quality of radiotherapy and imaging for international clinical trials recruiting children and adolescents with cancer throughout Europe. QUARTET combines the paediatric radiation oncology expertise of SIOPE with the infrastructure and experience of the European Organisation for Research and Treatment of Cancer to deliver radiotherapy quality assurance programmes for large, prospective, international clinical trials. QUARTET-affiliated trials include children and adolescents with brain tumours, neuroblastoma, sarcomas including rhabdomyosarcoma, and renal tumours including Wilms' tumour. With nine prospective clinical trials and two retrospective studies within the active portfolio in March 2022, QUARTET will collect one of the largest repositories of paediatric radiotherapy and imaging data, support the clinical assessment of radiotherapy, and evaluate the role and benefit of radiotherapy quality assurance for this cohort of patients within the context of clinical trials.

Adolescents and young adults with rhabdomyosarcoma treated in the European paediatric Soft tissue sarcoma Study Group (EpSSG) protocols: a cohort study.

BACKGROUND: Adolescent and young adult patients with rhabdomyosarcoma often have poorer outcomes than do children. We aimed to compare the findings of adolescent and young adult patients with children enrolled in two prospective clinical protocols. METHODS: This retrospective observational analysis was based on data from the European paediatric Soft tissue sarcoma Study Group (EpSSG) rhabdomyosarcoma 2005 trial (phase 3 randomised trial for localised rhabdomyosarcoma, open from April, 2006, to December, 2016) and the EpSSG MTS 2008 protocol (prospective, observational, single-arm study for metastatic rhabdomyosarcoma, open from June, 2010, to December, 2016), which involved 108 centres from 14 different countries in total. For this analysis, patients were categorised according to their age into children (age 0-14 years) and adolescents and young adults (age 15-21 years). For the analysis of adherence to treatment and toxicity, only patients with high-risk localised rhabdomyosarcoma included in the randomised part of the rhabdomyosarcoma 2005 study were considered. The primary outcome of event-free survival (assessed in all participants) was defined as the time from diagnosis to the first event (eg, tumour progression, relapse) or to the latest follow-up. Secondary outcomes were overall survival, response to chemotherapy, and toxicity. FINDINGS: Our analysis included 1977 patients, 1720 children (median age 4·7 years; IQR 2·6-8·4) and 257 adolescents and young adults (16·6 years; 15·8-18·0). 1719 patients were from the EpSSG rhabdomyosarcoma 2005 study (1523 aged <15 years and 196 aged 15-21 years) and 258 patients were from the EPSSG MTS 2008 study (197 aged <15 years and 61 aged 15-21 years). Adolescent and young adult patients were more likely than were children to have metastatic tumours (61 [23·7%] of 257 vs 197 [11·5%] of 1720; p<0·0001), unfavourable histological subtypes (119 [46·3%] vs 451 [26·2%]; p<0·0001), tumours larger than 5 cm (177 [68·9%] vs 891 [51·8%]; p<0·0001), and regional lymph node involvement (109 [42·4%] vs 339 [19·7%]; p<0·0001). Adolescent and young adult patients had lower 5-year event-free survival (52·6% [95% CI 46·3-58·6] vs 67·8% [65·5-70·0]; p<0·0001) and lower 5-year overall survival (57·1% [50·4-63·1] vs 77·9% [75·8-79·8]; p<0·0001) than did children. The multivariable analysis confirmed the inferior prognosis of patients aged 15-21 years (hazard ratios 1·48 [95% CI 1·20-1·83; p=0·0002] for poorer event-free survival and 1·73 [1·37-2·19; p<0·0001] for poorer overall survival). Modifications of administered chemotherapy occurred in 13 (15·3%) of 85 adolescents and young adults, and in 161 (21·4%) of 754 children. Grade 3-4 haematological toxicity and infection were observed more frequently in children than in adolescent and young adult patients. INTERPRETATION: This study found better outcomes for adolescent and young adult patients than those reported in epidemiological studies (eg, the EUROCARE-5 study reported 5-year overall survival of 39·6% for patients aged 15-19 years in the 2000-07 study period), suggesting that adolescent and young adult patients, at least up to age 21 years, can be treated with intensive paediatric therapies with no major tolerability issues and should be included in paediatric rhabdomyosarcoma trials. However, the inferior outcomes in adolescent and young adult patients compared with those in children, despite receiving similar therapy, suggest that a tailored and intensive treatment strategy might be warranted for these patients. FUNDING: Fondazione Città della Speranza.

The potential role of MR-guided adaptive radiotherapy in pediatric oncology: Results from a SIOPE-COG survey.

BACKGROUND AND PURPOSE: Magnetic resonance guided radiotherapy (MRgRT) has been successfully implemented for several routine clinical applications in adult patients. The purpose of this study is to map the potential benefit of MRgRT on toxicity reduction and outcome in pediatric patients treated with curative intent for primary and metastatic sites. MATERIALS AND METHODS: Between May and August 2020, a survey was distributed among SIOPE- and COG-affiliated radiotherapy departments, treating at least 25 pediatrics patients annually and being (candidate) users of a MRgRT system. The survey consisted of a table with 45 rows (clinical scenarios for primary (n = 28) and metastatic (n = 17) tumors) and 7 columns (toxicity reduction, outcome improvement, PTV margin reduction, target volume daily adaptation, online re-planning, intrafraction motion compensation and on-board functional imaging) and the option to answer by 'yes/no' . Afterwards, the Dutch national radiotherapy cohort was used to estimate the percentage of pediatric treatments that may benefit from MRgRT. RESULTS: The survey was completed by 12/17 (71% response rate) institutions meeting the survey inclusion criteria. Responders indicated an 'expected benefit' from MRgRT for toxicity/outcome in 7% (for thoracic lymphomas and abdominal rhabdomyosarcomas)/0% and 18% (for mediastinal lymph nodes, lymph nodes located in the liver/splenic hilum, and liver metastases)/0% of the considered scenarios for the primary and metastatic tumor sites, respectively, and a 'possible benefit' was estimated in 64%/46% and 47%/59% of the scenarios. When translating the survey outcome into a clinical perspective a toxicity/outcome benefit, either expected or possible, was anticipated for 55%/24% of primary sites and 62%/38% of the metastatic sites. CONCLUSION: Although the benefit of MRgRT in pediatric radiation oncology is estimated to be modest, the potential role for reducing toxicity and improving clinical outcomes warrants further investigation. This fits best within the context of prospective studies or registration trials.

High grade gliomas in young children: The South Thames Neuro-Oncology unit experience and recent advances in molecular biology and targeted therapies.

High grade gliomas (HGG) have a dismal prognosis with survival rates of 15-35%. Approximately 10-12% of pediatric HGG occur in young children and their molecular biology and clinical outcomes differ from those arising at older ages. We report on four children aged <5 years newly diagnosed with non-brainstem HGG between 2011 and 2018 who were treated with surgery and BBSFOP chemotherapy. Two died of tumor progression. The other two are still alive without radiotherapy at 3.8 and 3.9 years from diagnosis: one of whom remains disease-free off treatment; and the other one, whose tumor harbored a KCTD16:NTRK2 fusion, went on to receive larotrectinib. Additionally we review the general management, outcomes and latest updates in molecular biology and targeted therapies for young children with HGG. Infant gliomas can be stratified in molecular subgroups with clinically actionable oncogenic drivers. Chemotherapy-based strategies can avoid or delay the need for radiotherapy in young children with HGG. Harnessing the potential of NTRK, ALK, ROS1 and MET inhibitors offers the opportunity to optimize the therapeutic armamentarium to improve current outcomes for these children.

Rhabdomyosarcoma.

Rhabdomyosarcoma is a heterogeneous disease both in presentation and histology. Improvements in a multimodality therapy resulted in the improved overall survival for patients with a low-risk and intermediate-risk disease but not for patients with a metastatic disease. We reviewed and contrasted the North American and European practice patterns, though ultimately the principles of staging, surgery, radiation therapy, and chemotherapy are similar in both Children's Oncology Group and International Society of Paediatric Oncology treatment approaches. Efforts are underway to investigate improved local control rates in higher risk patients using radiation dose escalation strategies, and delayed primary excision in select cases. The prognostic significance of imaging-based chemotherapy response, proton therapy, novel biomarkers, and targeted drugs will be determined in upcoming clinical trials.

Quality assurance in radiation oncology.

The Children's Oncology Group (COG) has a strong quality assurance (QA) program managed by the Imaging and Radiation Oncology Core (IROC). This program consists of credentialing centers and providing real-time management of each case for protocol compliant target definition and radiation delivery. In the International Society of Pediatric Oncology (SIOP), the lack of an available, reliable online data platform has been a challenge and the European Society for Paediatric Oncology (SIOPE) quality and excellence in radiotherapy and imaging for children and adolescents with cancer across Europe in clinical trials (QUARTET) program currently provides QA review for prospective clinical trials. The COG and SIOP are fully committed to a QA program that ensures uniform execution of protocol treatments and provides validity of the clinical data used for analysis.

Rapid 4D-MRI reconstruction using a deep radial convolutional neural network: Dracula.

BACKGROUND AND PURPOSE: 4D and midposition MRI could inform plan adaptation in lung and abdominal MR-guided radiotherapy. We present deep learning-based solutions to overcome long 4D-MRI reconstruction times while maintaining high image quality and short scan times. METHODS: Two 3D U-net deep convolutional neural networks were trained to accelerate the 4D joint MoCo-HDTV reconstruction. For the first network, gridded and joint MoCo-HDTV-reconstructed 4D-MRI were used as input and target data, respectively, whereas the second network was trained to directly calculate the midposition image. For both networks, input and target data had dimensions of 256 × 256 voxels (2D) and 16 respiratory phases. Deep learning-based MRI were verified against joint MoCo-HDTV-reconstructed MRI using the structural similarity index (SSIM) and the naturalness image quality evaluator (NIQE). Moreover, two experienced observers contoured the gross tumour volume and scored the images in a blinded study. RESULTS: For 12 subjects, previously unseen by the networks, high-quality 4D and midposition MRI (1.25 × 1.25 × 3.3 mm3) were each reconstructed from gridded images in only 28 seconds per subject. Excellent agreement was found between deep-learning-based and joint MoCo-HDTV-reconstructed MRI (average SSIM ≥ 0.96, NIQE scores 7.94 and 5.66). Deep-learning-based 4D-MRI were clinically acceptable for target and organ-at-risk delineation. Tumour positions agreed within 0.7 mm on midposition images. CONCLUSION: Our results suggest that the joint MoCo-HDTV and midposition algorithms can each be approximated by a deep convolutional neural network. This rapid reconstruction of 4D and midposition MRI facilitates online treatment adaptation in thoracic or abdominal MR-guided radiotherapy.

Determining the incidence of interstitial pneumonitis and chronic kidney disease following full intensity haemopoetic stem cell transplant conditioned using a forward-planned intensity modulated total body irradiation technique.

PURPOSE/OBJECTIVE: Total body irradiation (TBI) remains a key component of conditioning for allogeneic haemopoietic stem cell transplant (HSCT), with interstitial pneumonitis (IP) and chronic kidney disease (CKD) important late sequelae. We undertook a retrospective service evaluation of TBI patients treated with a forward-planned intensity modulated radiotherapy technique (FP IMRT). MATERIAL/METHODS: 74 adult patients were identified; all received step and shoot FP IMRT TBI, 14.4 Gy in 8 fractions over 4 days. Mean doses to the lungs and kidneys were 12-12.5 Gy. Toxicities were defined as per CTCAE v4.0: IP as multilobar infiltrates on CT with symptoms of dyspnoea, and renal dysfunction as an Estimated Glomerular Filtration rate (eGFR) < 60 ml/min/1.73 m2 for > 3 months. Secondary endpoints were overall survival (OS), progression free survival (PFS), cumulative incidence of non-relapse mortality (NRM), relapse risk and of acute and chronic GvHD. RESULTS: Patients received treatment for the following diagnosis: ALL/LBL (n = 37); AML (n = 33), CML-BC (n = 2) and High grade NHL (n = 2). The rate of IP due to any cause was 30%; positive microbiological evidence in 73% (16 /22). Idiopathic IP was seen in 8%, with only 4% (n = 3) having IP Grade ≥ 3. Two (4%) of 52 long term survivors developed CKD, one with thrombotic microangiopathy. 4 year NRM was 16% (CI 11-32%); no treatment related deaths in matched sibling or umbilical cord blood HSCT. CONCLUSION: FP IMRT TBI, reducing dose to the lungs and kidneys, has lower rates of idiopathic IP and CKD compared to the literature. This technique is safe and effective conditioning for full intensity HSCT.

A rapid review of evidence and recommendations from the SIOPE radiation oncology working group to help mitigate for reduced paediatric radiotherapy capacity during the COVID-19 pandemic or other crises.

OBJECTIVE: To derive evidence-based recommendations for the optimal utilisation of resources during unexpected shortage of radiotherapy capacity. METHODS AND MATERIALS: We have undertaken a rapid review of published literature on the role of radiotherapy in the multimodality treatment of paediatric cancers governing the European practise of paediatric radiotherapy. The derived data has been discussed with expert paediatric radiation oncologists to derive a hierarchy of recommendations. RESULTS: The general recommendations to mitigate the potential detriment of an unexpected shortage of radiotherapy facilities include: (1) maintain current standards of care as long as possible (2) refer to another specialist paediatric radiotherapy department with similar level of expertise (3) prioritise use of existing radiotherapy resources to treat patients with tumours where radiotherapy has the most effect on clinical outcome (4) use chemotherapy to defer the start of radiotherapy where timing of radiotherapy is not expected to be detrimental (5) active surveillance for low-grade tumours if appropriate and (6) consider iso-effective hypofractionated radiotherapy regimens only for selected patients with predicted poor prognosis. The effectiveness of radiotherapy and recommendations for prioritisation of its use for common and challenging paediatric tumours are discussed. CONCLUSION: This review provides evidence-based treatment recommendations during unexpected shortage of paediatric radiotherapy facilities. It has wider applications for the optimal utilisation of facilities, to improve clinical outcome in low- and middle-income countries, where limited resources continue to be a challenge.

Management of vertebral radiotherapy dose in paediatric patients with cancer: consensus recommendations from the SIOPE radiotherapy working group.

Inhomogeneities in radiotherapy dose distributions covering the vertebrae in children can produce long-term spinal problems, including kyphosis, lordosis, scoliosis, and hypoplasia. In the published literature, many often interrelated variables have been reported to affect the extent of potential radiotherapy damage to the spine. Articles published in the 2D and 3D radiotherapy era instructed radiation oncologists to avoid dose inhomogeneity over growing vertebrae. However, in the present era of highly conformal radiotherapy, steep dose gradients over at-risk structures can be generated and thus less harm is caused to patients. In this report, paediatric radiation oncologists from leading centres in 11 European countries have produced recommendations on how to approach dose coverage for target volumes that are adjacent to vertebrae to minimise the risk of long-term spinal problems. Based on available information, it is advised that homogeneous vertebral radiotherapy doses should be delivered in children who have not yet finished the pubertal growth spurt. If dose fall-off within vertebrae cannot be avoided, acceptable dose gradients for different age groups are detailed here. Vertebral delineation should include all primary ossification centres and growth plates, and therefore include at least the vertebral body and arch. For partial spinal radiotherapy, the number of irradiated vertebrae should be restricted as much as achievable, particularly at the thoracic level in young children (<6 years old). There is a need for multicentre research on vertebral radiotherapy dose distributions for children, but until more valid data become available, these recommendations can provide a basis for daily practice for radiation oncologists who have patients that require vertebral radiotherapy.

Dosimetric accuracy of dynamic couch rotation during volumetric modulated arc therapy (DCR-VMAT) for primary brain tumours.

Radiotherapy treatment plans using dynamic couch rotation during volumetric modulated arc therapy (DCR-VMAT) reduce the dose to organs at risk (OARs) compared to coplanar VMAT, while maintaining the dose to the planning target volume (PTV). This paper seeks to validate this finding with measurements. DCR-VMAT treatment plans were produced for five patients with primary brain tumours and delivered using a commercial linear accelerator (linac). Dosimetric accuracy was assessed using point dose and radiochromic film measurements. Linac-recorded mechanical errors were assessed by extracting deviations from log files for multi-leaf collimator (MLC), couch, and gantry positions every 20 ms. Dose distributions, reconstructed from every fifth log file sample, were calculated and used to determine deviations from the treatment plans. Median (range) treatment delivery times were 125 s (123-133 s) for DCR-VMAT, compared to 78 s (64-130 s) for coplanar VMAT. Absolute point doses were 0.8% (0.6%-1.7%) higher than prediction. For coronal and sagittal films, respectively, 99.2% (96.7%-100%) and 98.1% (92.9%-99.0%) of pixels above a 20% low dose threshold reported gamma <1 for 3% and 3 mm criteria. Log file analysis showed similar gantry rotation root-mean-square error (RMSE) for VMAT and DCR-VMAT. Couch rotation RMSE for DCR-VMAT was 0.091° (0.086-0.102°). For delivered dose reconstructions, 100% of pixels above a 5% low dose threshold reported gamma <1 for 2% and 2 mm criteria in all cases. DCR-VMAT, for the primary brain tumour cases studied, can be delivered accurately using a commercial linac.

Psychosocial well-being of long-term survivors of pediatric head-neck rhabdomyosarcoma.

BACKGROUND: Head and neck rhabdomyosarcoma (HNRMS) survivors are at risk to develop adverse events (AEs). The impact of these AEs on psychosocial well-being is unclear. We aimed to assess psychosocial well-being of HNRMS survivors and examine whether psychosocial outcomes were associated with burden of therapy. PROCEDURE: Sixty-five HNRMS survivors (median follow-up: 11.5 years), treated in the Netherlands and the United Kingdom between 1990 and 2010 and alive ≥2 years after treatment visited the outpatient multidisciplinary follow-up clinic once, in which AEs were scored based on a predefined list according to the Common Terminology Criteria for Adverse Events. Survivors were asked to complete questionnaires on health-related quality of life (HRQoL; PedsQL and YQOL-FD), self-perception (KIDSCREEN), and satisfaction with appearances (SWA). HRQoL and self-perception scores were compared with reference values, and the correlation between physician-assessed AEs and psychosocial well-being was assessed. RESULTS: HNRMS survivors showed significantly lower scores on PedsQL school/work domain (P ≤ 0.01, P = 0.02, respectively), YQOL-FD domains negative self-image and positive consequences (P ≤ 0.01, P = 0.04, respectively) compared with norm data; scores on negative consequences domain were significantly higher (P = 0.03). Over 50% of survivors negatively rated their appearances on three or more items. Burden of AEs was not associated with generic HRQoL and self-perception scores, but was associated with disease-specific QoL (YQOL-FD). CONCLUSION: In general, HRQoL in HNRMS survivors was comparable to reference groups; however, survivors did report disease-specific consequences. We therefore recommend including specific questionnaires related to difficulties with facial appearance in a systematic monitoring program to determine the necessity for tailored care.

Functional diversity and cooperativity between subclonal populations of pediatric glioblastoma and diffuse intrinsic pontine glioma cells.

The failure to develop effective therapies for pediatric glioblastoma (pGBM) and diffuse intrinsic pontine glioma (DIPG) is in part due to their intrinsic heterogeneity. We aimed to quantitatively assess the extent to which this was present in these tumors through subclonal genomic analyses and to determine whether distinct tumor subpopulations may interact to promote tumorigenesis by generating subclonal patient-derived models in vitro and in vivo. Analysis of 142 sequenced tumors revealed multiple tumor subclones, spatially and temporally coexisting in a stable manner as observed by multiple sampling strategies. We isolated genotypically and phenotypically distinct subpopulations that we propose cooperate to enhance tumorigenicity and resistance to therapy. Inactivating mutations in the H4K20 histone methyltransferase KMT5B (SUV420H1), present in <1% of cells, abrogate DNA repair and confer increased invasion and migration on neighboring cells, in vitro and in vivo, through chemokine signaling and modulation of integrins. These data indicate that even rare tumor subpopulations may exert profound effects on tumorigenesis as a whole and may represent a new avenue for therapeutic development. Unraveling the mechanisms of subclonal diversity and communication in pGBM and DIPG will be an important step toward overcoming barriers to effective treatments.

Fusion status in patients with lymph node-positive (N1) alveolar rhabdomyosarcoma is a powerful predictor of prognosis: Experience of the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG).

BACKGROUND: Alveolar rhabdomyosarcoma (aRMS) with lymph node involvement (N1 classification) accounts for up to 10% of all cases of RMS. The prognosis is poor, and is comparable to that of distant metastatic disease. In the European Paediatric Soft Tissue Sarcoma Study Group (EpSSG) RMS2005 protocol, patients with a histologic diagnosis of aRMS/N1 received intensified chemotherapy with systematic locoregional treatment. METHODS: Patients with aRMS/N1 were enrolled prospectively after primary surgery/biopsy and fusion status was assessed in tumor samples. All patients received 9 cycles of induction chemotherapy and 6 months of maintenance therapy. Local treatment included radiotherapy to the primary site and lymph nodes with or without secondary surgical resection. RESULTS: A total of 103 patients were enrolled. The clinical characteristics of the patients were predominantly unfavorable: 90% had macroscopic residual disease after initial surgery/biopsy, 63% had locally invasive tumors, 77% had a tumor measuring >5 cm, and 81% had disease at unfavorable sites. Fusion genes involving forkhead box protein O1 (FOXO1) were detected in 56 of 84 patients. Events occurred in 52 patients: 43 developed disease recurrence, 7 had disease that was refractory to treatment, and 2 patients developed second neoplasms. On univariate analysis, unfavorable disease site, tumor invasiveness, Intergroup Rhabdomyosarcoma Study group III, and fusion-positive status correlated with worse prognosis. The 5-year event-free survival rate of patients with fusion-positive tumors was 43% compared with 74% in patients with fusion-negative tumors (P = .01). On multivariate analysis, fusion positivity and tumor invasiveness proved to be unfavorable prognostic markers. CONCLUSIONS: Fusion status and tumor invasiveness appear to have a strong impact on prognosis in patients with aRMS/N1. Fusion status will be used to stratify these patients in the next EpSSG RMS study, and treatment will be intensified in patients with fusion-positive tumors. Cancer 2018. © 2018 American Cancer Society.