Paulino, Arnold C

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.

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.

AbstractBackgroundPediatric brain tumor survivors are at risk for poor social outcomes. It remains unknown whether cognitive sparing with proton radiotherapy (PRT) supports better social outcomes relative to photon radiotherapy (XRT). We hypothesized that survivors treated with PRT would outperform those treated with XRT on measures of cognitive and social outcomes. Further, we hypothesized that cognitive performance would predict survivor social outcomes.ProcedureSurvivors who underwent PRT (n = 38) or XRT (n = 20) participated in a neurocognitive evaluation >1 year post radiotherapy. Group differences in cognitive and social functioning were assessed using analysis of covariance (ANCOVA). Regression analyses examined predictors of peer relations and social skills.ResultsAge at evaluation, radiation dose, tumor diameter, and sex did not differ between groups (all p > .05). XRT participants were younger at diagnosis (XRT M = 5.0 years, PRT M = 7.6 years) and further out from radiotherapy (XRT M = 8.7 years, PRT M = 4.6 years). The XRT group performed worse than the PRT group on measures of processing speed (p = .01) and verbal memory (p < .01); however, social outcomes did not differ by radiation type. The proportion of survivors with impairment in peer relations and social skills exceeded expectation; χ2(1) = 38.67, p < .001; χ2(1) = 5.63, p < .05. Household poverty predicted peer relation difficulties (t = 2.18, p < .05), and verbal memory approached significance (t = −1.99, p = .05). Tumor diameter predicted social skills (t = −2.07, p < .05).ConclusionsRegardless of radiation modality, survivors are at risk for social challenges. Deficits in verbal memory may place survivors at particular risk. Results support monitoring of cognitive and social functioning throughout survivorship, as well as consideration of sociodemographic risk factors.

Abstract Background Brainstem toxicity after radiation therapy (RT) is a devastating complication and a particular concern with proton radiation (PBT). We investigated the incidence and clinical correlates of brainstem injury in pediatric brain tumors treated with PBT. Methods All patients &lt;21 years with brain tumors treated with PBT at our institution from 2007–2019, with a brainstem Dmean &gt;30 Gy and/or Dmax &gt;50.4 Gy were included. Symptomatic brainstem injury (SBI) was defined as any new or progressive cranial neuropathy, ataxia, and/or motor weakness with corresponding radiographic abnormality within brainstem. Results A total of 595 patients were reviewed and 468 (medulloblastoma = 200, gliomas = 114, ependymoma = 87, ATRT = 43) met our inclusion criteria. Median age at RT was 6.3 years and median prescribed RT dose was 54Gy [RBE]. Fifteen patients (3.2%) developed SBI, at a median of 4 months after RT. Grades 2, 3, 4, and 5 brainstem injuries were seen in 7, 5, 1, and 2 patients respectively. Asymptomatic radiographic changes were seen in 51 patients (10.9%). SBI was significantly higher in patients with age ≤3 years, female gender, ATRT histology, patients receiving high-dose chemotherapy with stem cell rescue, and those not receiving craniospinal irradiation. Patients with SBI had a significantly higher V50–52. In 2014, our institution started using strict brainstem dose constraints (Dmax ≤57 Gy, Dmean ≤52.4 Gy, and V54≤10%). There was a trend towards decrease in SBI from 4.4% (2007-2013) to 1.5% (2014–2019) (P = .089) without affecting survival. Conclusion Our results suggest a low risk of SBI after PBT for pediatric brain tumors, comparable to photon therapy. A lower risk was seen after adopting strict brainstem dose constraints.

Background: Pediatric brain tumor survivors are at risk for poor social outcomes. It remains unknown whether cognitive sparing with proton radiotherapy (PRT) supports better social outcomes relative to photon radiotherapy (XRT). We hypothesized that survivors treated with PRT would outperform those treated with XRT on measures of cognitive and social outcomes. Further, we hypothesized that cognitive performance would predict survivor social outcomes. Procedure: Survivors who underwent PRT (n=38) or XRT (n=20) participated in a neurocognitive evaluation >1 year post-radiotherapy. Group differences in cognitive and social functioning were assessed using ANCOVA. Regression analyses examined predictors of peer relations and social skills. Results: Age at evaluation, radiation dose, tumor diameter, and sex did not differ between groups (all p>0.05). However, XRT participants were younger at diagnosis (XRT M=5.0 years, PRT M=7.6 years) and further out from radiotherapy (XRT M=8.7 years, PRT M=4.6 years). The XRT group performed worse than the PRT group on measures of processing speed (p=0.01) and verbal memory (p<0.01); however, social outcomes did not differ by radiation type. The proportion of survivors with impairment in peer relations and social skills exceeded expectation (2(1)=38.67, p<0.001; 2(1)=5.63, p<0.05), and verbal memory approached significance as a unique predictor of peer relations (t=-2.01, p=0.05). Total tumor RT dose significantly predicted social skills (t=-2.23, p<0.05). Conclusions: Regardless of radiation modality, survivors are at risk for social challenges, with one-quarter being socially excluded or undervalued. Deficits in verbal memory may place survivors at particular risk. Results support monitoring of cognitive and social functioning throughout survivorship.