Paulino, Arnold C.

ABSTRACT Pediatric radiation therapy presents unique challenges compared to adult treatments, including those of immobilization, potential need for sedation, and the critical importance of accurate, reproducible positioning. Additionally, heightened attention to imaging doses is necessary to minimize long‐term toxicity in survivors. Many of these challenges must be addressed during the process of simulation. This report provides guidelines for pediatric radiotherapy simulation from the Children's Oncology Group. These guidelines cover all anatomic sites and include recommendations for photon and proton therapies, as well as specialized procedures such as stereotactic body radiation therapy, brachytherapy, and total body irradiation. These guidelines are presented as recommendations rather than prescriptive standards as the practice will vary depending on patient age, diagnosis, clinical judgment, and institutional resources.

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.

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 Background Diffuse intrinsic pontine glioma (DIPG) carries a poor prognosis with a median survival of less than 12 months. Key molecular features include histone H3 mutation (K27M) and AKT pathway dysregulation. There is currently no curative treatment. Methods This is a Phase I study of vorinostat and temsirolimus in newly diagnosed (Stratum 1) and progressive (Stratum 2) DIPG (NCT02420613). The primary aims are to determine the safety, maximum tolerated dose (MTD), and toxicities. A modified 3 + 3 design was used to establish the MTD, where the first three patients were assigned the first dose level regardless of stratum. Stratum 1 received radiotherapy with vorinostat, followed by up to 10 cycles of vorinostat and temsirolimus. Stratum 2 received up to 12 cycles of vorinostat and temsirolimus. Vorinostat was administered at a fixed dose of 230 mg/m 2 daily on Days 1–8, and temsirolimus was administered on Days 1 and 8 at 25 mg/m 2 (Dose level 1) or 35 mg/m 2 (Dose level 2). Results Six patients were enrolled, three in each stratum. No dose‐limiting toxicity was observed, and most adverse effects were limited to Grades 1 or 2, including fatigue, myelosuppression, hyperlipidemia, hyperglycemia, elevated creatinine, nausea, vomiting, and headache. One patient experienced Grade 3 leukopenia. In the study, the MTD with acceptable toxicity was vorinostat 230 mg/m 2 and temsirolimus 35 mg/m 2 . Conclusions Overall, the combination of temsirolimus and vorinostat is well‐tolerated and safe, prompting the need for larger studies to investigate its efficacy.

Abstract BACKGROUND Diffuse intrinsic pontine glioma (DIPG) carries a poor prognosis with a median survival of less than 12 months. Histone mutation, K27M, and AKT pathway dysregulation play key roles in tumorigenesis. There is no curative treatment with radiation therapy, which currently remains the standard treatment. METHODS This is a phase I study of vorinostat and temsirolimus in newly diagnosed (stratum 1) and progressive (stratum 2) DIPG. The primary aims are to determine the safety, maximum tolerated dose, and toxicities (NCT02420613). Stratum 1 received radiation concurrently with vorinostat, followed by vorinostat and temsirolimus for up to 10 cycles. Stratum 2 received vorinostat and temsirolimus for up to 12 cycles. In stratum 1, vorinostat was administered daily at 230 mg/m2. The maintenance phase (both strata) included concurrent vorinostat 230 mg/m2 daily and temsirolimus 25 or 35 mg/m2 (Days 1 and 8). RESULTS Six patients were enrolled, three in each stratum. Three of the six patients had confirmed H3 K27M mutations. No dose-limiting toxicity was observed, and most adverse effects were limited to grades 1 or 2, including fatigue, nausea, vomiting, myelosuppression, hyperlipidemia, hyperglycemia, elevated liver enzymes, and creatinine. However, one patient experienced grade 3 leukopenia. Two of the three patients in stratum 1 showed evidence of radiographic response after the chemoradiation phase, of whom one patient had progression-free survival of 12 months and completed the 10 maintenance cycles. All patients at stratum 2 had disease progression with no radiographic response. CONCLUSION Overall, the combination of temsirolimus and vorinostat is well tolerated and safe, prompting the need for larger studies to investigate its efficacy. Due to the small number of patients, the study’s findings are limited, and trends in efficacy should be interpreted with caution.

AbstractRadiation oncology is an integral part of the multidisciplinary team caring for children with cancer. The primary goal of our committee is to enable the delivery of the safest dose of radiation therapy (RT) with the maximal potential for cure, and to minimize toxicity in children by delivering lower doses to normal tissues using advanced technologies like intensity‐modulated RT (IMRT) and proton therapy. We provide mentorship for y ators and are actively involved in educating the global radiation oncology community. We are leaders in the effort to discover novel radiosensitizers, radioprotectors, and advanced RT technologies that could help improve outcomes of children with cancer.

Abstract Background Medulloblastoma in adults is rare and treatment decisions are largely driven from pediatric literature. We sought to characterize recurrent medulloblastoma in adults. Methods From a single-institution dataset of 200 adult patients diagnosed with medulloblastoma during 1978–2017, those with recurrence were analyzed for clinical features, treatment, and outcome. Results Of the 200 patients, 82 (41%) with median age of 29 years (18–59) had recurrence after a median follow-up time of 8.4 years (95% CI = 7.1, 10.3). Of these, 30 (37%) were standard-risk, 31 (38%) were high-risk, and 21 (26%) had unknown-risk diseases at the time of initial diagnosis. Forty-eight (58%) presented with recurrence outside the posterior fossa, of whom 35 (43%) had distant recurrence only. Median Progression-free survival (PFS) and OS from initial surgery were 33.5 and 62.4 months, respectively. Neither PFS nor OS from initial diagnosis differed between the standard-risk and high-risk groups in those who experience recurrence (P = .505 and .463, respectively). Median OS from first recurrence was 20.3 months, also with no difference between the standard-risk and high-risk groups (P = .518). Recurrences were treated with combinations of re-resection (20 patients; 25%), systemic chemotherapy (61 patients; 76%), radiation (29 patients; 36%), stem cell transplant (6 patients; 8%), and intrathecal chemotherapy (4 patients; 5%). Patients who received radiation at recurrence had better OS (32.9 months) than those who did not (19.2 months) (P = .034). Conclusions Recurrent medulloblastoma in adults has a poor prognosis irrespective of initial risk stratification. Recurrence commonly arises outside the posterior fossa years after initial diagnosis.