Evaluation of the risk-benefit ratio of new techniques of photon and proton radiotherapy on organs at risk, integral dose and growing spine, in treatment of abdominal neuroblastoma in children ; Évaluation du rapport bénéfice risque des nouvelles techniques d'irradiation en photons et protons sur les organes de proximité, la dose intégrale et le rachis en croissance dans le traitement du neuroblastome abdominal de l'enfant

Background: radiotherapy is part of adjuvant treatment of high-risk neuroblastoma in children. Second cancer risk and risk of late sequelae, especially on growing spine, are the two main problems in this population, which are critical to choose the right technique of treatment. Intensity modulated radiotherapy offers a better conformation of delivered dose around the tumor. Proton therapy has a ballistic advantage which remains to be evaluated. The aim of the study was to compare in terms of benefit-risk ratio three radiotherapy techniques: conformal 3D radiotherapy (3D-RT), intensity modulated radiotherapy (IMRT), and pencil beam scanning proton therapy (IMPT). Methods: seven consecutive patients treated at our institution for an abdominal neuroblastoma by helical tomotherapy were included. Analysis was made on: doses received by organs at risk, including vertebrae and intravertebral structures, integral dose, low-doses volumes, normal tissue complication probability calculated from adult radiobiological data, and the application of a predictive model of growth sequelae established from a literature review. Results: three out of five of the parameters evaluated were in favor of IMPT: doses received to organs at risk, estimation of second cancer risk and NTCP. On growing spine, higher lateral dose gradients were observed by IMPT, but dose gradients were low by all techniques (<1Gy). Same stature loss were predicted by the model for the three techniques. Conclusion: subject to the limitations of this study, IMPT seems to have the best risk-benefit ratio in treatment of abdominal neuroblastoma in children. ; Introduction : la radiothérapie fait partie du traitement du neuroblastome de haut risque chez l'enfant. Les risques de second cancer et de séquelles tardives, notamment sur le rachis en croissance, sont les problèmes qui doivent guider le choix de la technique. La modulation d'intensité permet de mieux conformer la dose à la forme tumorale. La protonthérapie offre un avantage balistique dont l'impact reste ...