Childhood Cancer Data Initiative Annual Symposium (Abstract Registration): Submission #61

Abstract: Proton radiotherapy has emerged as the preferred radiotherapy modality for some cancers, especially in children. Proton radiotherapy is expected to reduce the risk of subsequent cancer and other adverse long-term health effects compared to photon radiotherapy because the physical properties of protons allow for lower radiation exposure to surrounding normal tissues. However, the magnitude of the purported reduction in risk remains uncertain, and no randomized clinical trials have compared the two radiotherapy types in children, who are more susceptible to the late effects of radiation compared to adults. Observational studies, while generally reassuring, have had important methodological limitations. CCDI funding enabled establishment of the NCI Pediatric Proton and Photon Therapy Comparison Cohort, a large-scale multicenter study with the primary aim to compare the risk of subsequent cancers in pediatric cancer patients treated with proton versus photon radiotherapy. Patient and treatment data, including electronic radiotherapy records, are being collected for eligible patients treated 2006-2025 at 17 participating centers. Long-term follow-up for incident second cancers will be conducted via linkage with state cancer registries. State-of-the-art radiation dose reconstruction methods developed for application in this cohort will allow for assessment of radiation dose-response and dose volume effects. Our poster will discuss the status of ongoing clinical and radiotherapy data collection and describe the current study population by demographic and treatment factors. Research from this cohort is expected to inform clinical practice for pediatric cancer patients by providing the first large-scale systematic comparison of subsequent cancer risk after proton compared to photon therapy.