Citations

Abstract Background In children with non-metastatic atypical teratoid/rhabdoid tumor (ATRT), proton therapy is increasingly utilized worldwide due to the radiosensitivity of afflicted young patients. General questions persist, however, surrounding dose and volume of radiotherapy. Methods Between 2009-2024, 39 children from a single institution with non-metastatic intracranial ATRT received focal proton therapy at a median age of 2.4 years (range 0.7-19). Twenty-two patients had supratentorial tumors and 27 had gross/near total resection prior to radiation. Most common chemotherapy regimens were ACNS0333 and SJYC07 (n = 10 each) and Dana-Farber (n = 6). Four patients received consolidative high-dose chemotherapy after radiation. The median radiation dose was 50.4 Gy (range, 50.4-54). The cumulative incidence method assessed freedom from selected endpoints.The Fine-Gray method assessed the level of statistical significance between levels of selected prognostic factors. Results With a median followup of 5.2 years (range 0.5-16.2), the 5-yr overall survival, progression-free survival, and local control was 63%, 64%, and 97%, respectively. Thirteen patients developed isolated leptomeningeal failure as first site of recurrence. Only subtotal resection was significantly associated with local recurrence (100% vs 92%, p < 0.05). Patient age, tumor site, extent of resection, radiation dose, and chemotherapy regimen were otherwise not significantly associated with disease control or survival. Four patients experienced symptomatic radiation necrosis, including 1 death: Three of 4 cases received 54 Gy and consolidative intrathecal methotrexate (n = 2) or high dose ACNS0333 intravenous chemotherapy (n = 1, fatal) after radiation. The other patient received 50.4 Gy and necrosis was immediately preceded by ventriculoperitoneal shunt failure. Six patients developed hearing loss requiring aids. One patient developed radiation-induced meningioma a decade following treatment. Conclusion This represents the largest experience reporting 5-year outcomes following focal radiation in children with non-metastatic intracranial ATRT. When applied with a variety of modern chemotherapy regimens in real-world settings, focal proton therapy at a dose of 50.4 Gy may offer the best therapeutic ratio but does not eliminate serious toxicity. If avoidance of craniospinal radiation remains an ongoing priority, further improvement in survival will depend upon systemic therapy.

ABSTRACT The local treatment of bladder and prostate rhabdomyosarcoma is a multidisciplinary decision, incorporating elements of patient age, tumor size and location, nodal involvement, and access to local expertise and technology. The relative absence of long‐term bladder and bowel function outcome data complicates discussions, particularly given improved survival rates and development of new surgical and radiotherapy techniques. These INSTRuCT guidelines, a collaboration of the Children's Oncology Group, Soft Tissue Sarcoma Committee, European Pediatric Soft Tissue Sarcoma Study Group, and the Cooperative Weichteilsarkom Studiengruppe, reflect international expert consensus and are intended to inform practice, generate discussion, and highlight areas of future inquiry.

Abstract Purpose/Objective(s) To report outcomes for disseminated Medulloblastoma (stage M1-M3) who received radiation (RT) on the Pediatric Proton/Photon Consortium Registry (PPCR). Materials/Methods 71 patients were included with either M1 (6), M2 (21), or M3 (44) Medulloblastoma on PPCR. Survival (OS, Overall; EFS, Event Free) analyses were performed using the Kaplan Meier method and log rank p-values from RT start. Median follow up was calculated using the reverse Kaplan Meier method. Results Median age at RT was 7.5 years (range 2.4-21.89) and the median follow up was 4.3 years. Histology was classic (52), diffuse anaplasia (12), focal anaplasia (5), desmoplastic nodular (1), or other (1). Treatment included surgery, chemotherapy with or without stem cell support, and RT. 54 patients had gross total resection (GTR) or near total resection (NTR); 14 had subtotal resection (STR). Pre-RT chemotherapy was given in 69 (97.1%) patients; 23 had myeloablative chemotherapy with stem cell support. The 5 and 10-year OS of the entire cohort were 73% and 65%, and 5 and 10-year EFS were 65% and 59%. Patients with progression prior to RT (10 patients) had inferior OS (5-year OS 44%) compared to patients without progression pre-RT (5-year OS 78%, p = 0.045). There was a trend for better OS (p = 0.07) and improved EFS (p = 0.043) for M2 stage. GTR/NTR did not impact OS (p = 0.75) or EFS (p = 0.97) compared to STR. Craniospinal (CSI) radiation (70 patients, 99%) doses were: £ 23.4Gy (11.4%), 23.5Gy-36Gy (11.4%), or ³ 36Gy (74.3%). Patients receiving CSI ³ 36Gy had superior OS (p = 0.043), with 5 and 10-year OS of 82% and 71% compared to 5 and 10-year OS of 52% and 52% for lower dose CSI. Conclusion Full dose CSI (36Gy) for M1-M3 medulloblastoma was associated with excellent long-term survival this series, whereas lower dose CSI and progression prior to RT had inferior outcomes.

ABSTRACT Background Proton beam therapy (PBT) offers dosimetric advantages in pediatric radiotherapy by reducing radiation exposure to healthy tissues. However, broad implementation raises important ethical, logistical, and equity considerations, especially in settings with limited access to advanced technologies. Procedure This position paper by the Paediatric Radiation Oncology Society (PROS) reviews the clinical rationale for selecting radiotherapy modalities in children, with a specific focus on ethical utilization of PBT. The document synthesizes evidence on the benefits and limitations of modern photon and proton therapies, explores disparities in access, outlines the role of local pediatric radiation oncologists, and addresses the impact of industry‐driven messaging on family decision‐making. Results While PBT offers clinical benefit in selecting pediatric cancers, high‐quality photon‐based treatments such as IMRT and VMAT remain effective and widely accessible alternatives. The referral and evaluation process for PBT is complex and may introduce treatment delays. Travel and financial burdens can exacerbate disparities. PROS underscores the critical role of local pediatric radiation oncologists in counseling families, and calls for balanced, evidence‐based communication from providers and industry stakeholders. Conclusions PROS advocates for an ethical, equitable, and evidence‐informed approach to radiotherapy modality selection in children, reflecting holistic considerations beyond dosimetry. Proton therapy should be pursued when clinically indicated and accessible without compromising timely care. Investment in a comprehensive radiation therapy infrastructure, including professional education, collaborative research, and responsible public messaging, is essential to optimize pediatric cancer outcomes globally.

ABSTRACTIntroductionProton beam therapy (PT) offers a targeted approach to treating pediatric tumors by minimizing radiation exposure to surrounding healthy tissue. However, the specific toxicity profile associated with it remains underexplored. This study aims to investigate the incidence and risk factors of acute and late treatment‐related toxicities following PT in pediatric patients with pelvic tumors.MethodsUsing data from the Pediatric Proton Consortium Registry (PPCR), we analyzed 126 pediatric patients who underwent PT for pelvic tumors. We assessed the incidence of gastrointestinal (GI), genitourinary (GU), and musculoskeletal (MSK) toxicities at baseline, during treatment, and across follow‐up intervals.ResultsAcute toxicities were observed in 61.9% of patients posttreatment, with new GI, GU, and MSK toxicities occurring in 54.3%, 9.7%, and 7.0% of baseline toxicity‐free patients, respectively. Follow‐up indicated that 20.6%, 22.2%, and 13.5% of patients developed late GI, GU, and MSK toxicities, respectively. Use of passive scattering proton therapy and radiation to the abdomen were significant predictors of GI toxicity development, while higher radiation dose was associated with MSK toxicity development.ConclusionOur findings demonstrate the safety profile of PT among pediatric patients while identifying specific risk factors, such as passive scattering proton therapy and abdominal irradiation, that contribute to increased GI toxicity. While proton therapy appears to be a well‐tolerated treatment option, the observed toxicity rates highlight the need for continued monitoring and long‐term follow‐up.

AbstractPatients with resectable Ewing sarcoma (ES) in select sites, such as the pelvis or chest wall, have a higher risk of positive microscopic margins following surgery. AEWS1031 was the first North American/Australasia ES cooperative group trial allowing standardized preoperative radiotherapy, intended to minimize the morbidity of combined modality local tumor control as well as improve the likelihood of clear surgical margins. In this study, we found that the use of low‐dose preoperative radiation to a smaller target volume resulted in a high rate of R0 resection. The robust pathologic response rate strengthens existing evidence illustrating the radiosensitivity of Ewing sarcoma.

ABSTRACT In 2005, the Paediatric Radiation Oncology Society (PROS), a multi‐professional association to promote radiotherapy for children and young people, was created. Its mission has been to educate those involved in this field, and to improve the standards of radiation oncology care for children, adolescents, and young adults across the globe, not least in less privileged settings where the majority of the world's children, and most with cancer, live. Through regular congresses, and joint meetings with the International Society of Paediatric Oncology (SIOP), PROS has facilitated a focus on this treatment modality, and advocated on behalf of those who might benefit from it.

Abstract Purpose: Embryonal tumor with multilayered rosettes (ETMR) is a rare pediatric CNS embryonal tumor with poor survival. The Pediatric Proton/Photon Consortium Registry (PPCR) was queried for outcomes data from prospectively consenting pediatric patients with ETMR treated with proton radiation therapy (RT). Methods: 20 patients (2013-2021) at 9 institutions had ETMR; 2 with prior RT were excluded from statistical analyses (PPCR ETMR, N=18). Overall Survival (OS) and Event Free Survival (EFS) analyses were performed using the Kaplan-Meier method and log-rank values. Median follow-up was calculated using the reverse Kaplan-Meier method. Results: Median age at RT was 3.0 years (1.7-12.2); median follow-up was 55.5 months (2.6-119.4). 8 patients (44%) expired and 6 patients (33%) are surviving ≥55 months. 11 (61%) patients received systemic therapy with stem cell support. The majority (89%) had focal RT, while 2 patients received craniospinal irradiation (CSI). 4-year OS and EFS were 59.6% and 54.2%, respectively. Local control (LC) at 4 years was 81%. No differences in OS or EFS were observed for receipt of systemic therapy with stem cell support (p=0.361, p=0.57), progression prior to RT (p=0.127, p=0.18), or surgery to RT ≥200 days (p=0.35, p=0.254). Symptomatic radionecrosis was not reported. Conclusion: Focal proton RT provided effective local control as part of multimodality therapy for ETMR, with encouraging survival for this rare and often infant age tumor. Outcomes for CSI were limited to 2 patients treated upfront, and 1 patient receiving salvage CSI for disseminated relapse after focal RT who is surviving >1 year. Trial: DFCI protocol 12-103, clinicaltrials.gov NCT01696721, date of registration 9/27/2012

Trends in diagnostic biopsy sample collection approaches for primary bone sarcomas have shifted in the past 2 decades. Although open/incisional biopsies used to be the predominant approach to obtain diagnostic material for Ewing sarcoma and osteosarcoma, image-guided core needle biopsies have increased in frequency and are safe for patients. These procedures are less invasive and reduce recovery times but have potential limitations. The quantity and quality of tissue obtained through these procedures vary between institutions. Acquired viable tissue volumes can be low, limiting the conduct of downstream expanded clinical workup, molecular analyses, and research. Patients with advanced Ewing sarcoma and osteosarcoma continue to have overall poor outcomes despite dose-intensive cytotoxic chemotherapy. The biology of treatment resistance is not currently well understood, partly due to limited availability of relevant tissue to study. There is a need for access to quality tumor specimens for molecular and other analyses to identify high-risk tumor subsets and drive discovery to improve patient outcomes. Given broad variability in bone tumor tissue procurement and processing across member institutions, the Children’s Oncology Group Bone Tumor Committee convened a multidisciplinary group of experts to outline the current and near-future tissue needs for optimal clinical care and access to research platforms. The goal of this working group was to provide high-level guidance on biopsy practices that safely meet these evolving needs. Harmonizing tissue collection practices is paramount to improving the care of children, adolescents, and young adults diagnosed with Ewing sarcoma and osteosarcoma.