Medulloblastoma is an excellent candidate for proton therapy

Medulloblastoma: optimizing care with a multidisciplinary approach, Thomas A, Noël G

(…) In the last decade, the use of proton therapy has rapidly increased as a result of its capacity to better spare organs at risk by eliminating the exit radiation dose due to the characteristic dose distribution of the proton beam modeled by the Bragg peak. This treatment is particularly relevant in childhood malignancies since it offers the promise of decreased late radiation-related morbidities, especially second neoplasms. Medulloblastoma, specifically due to a particularly large irradiation field, is an excellent candidate for proton therapy. Indeed, protons eliminate the dose of exit radiation into the chest, abdomen, and pelvis as well as the cochlea, pituitary, and hypothalamus of children after CSI. Translation into quality of life (QoL) has been studied in a prospective trial. QoL scores were found to improve over time after proton CSI, and after 5 years, children-reported scores were statistically similar to those of healthy children, but the parent-reported scores remained statistically lower than those reported by the parents of healthy children. To evaluate the superiority of proton therapy in medulloblastoma treatment with an evidence-based approach, a review recently compared the outcomes of pediatric medulloblastoma patients between proton- and photon-mediated CSI, and revealed the advantage of proton therapy in organs at risk sparing, normal organ dysfunction, and secondary malignancy risks compared to various (mostly 3D-CRT) photon techniques. A comparison of target coverage between both radiation modalities showed either similar or better results with proton therapy. However, proton therapy is a modern radiation modality, and the earliest study considered in this review was from 1997. For that reason, data regarding late toxicity after proton therapy are not available. On the other hand, we cannot ignore that second neoplasms after CSI mostly occur in the neuraxis, and this effect cannot be avoided with any irradiation modality as long as CSI is performed. The only way to determine with any certainty whether proton therapy should be developed as a standard of care for CSI would be through a prospective randomized controlled trial comparing both treatment modalities. Such a trial should include cost-effectiveness analysis since proton therapy is undoubtedly associated with higher initial infrastructural costs than those for photon therapy. At the present time, proton therapy remains a limited resource, and socioeconomic factors impact access to this treatment. (…)

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