Long-term Cognitive and Functional Impact of Proton-therapy or Modern Fractionated Radiotherapy in Cavernous Sinus Meningioma: An Open-label Randomized 1:1 Phase III Study

Cavernous sinus meningiomas are close to optic nerve, pituitary gland, cranial nerve, and hippocampi. The doses delivered to these structures are crucial and radiotherapy of cavernous sinus meningiomas exposes patients to late secondary effects (pituitary deficit, nerve palsy, cognitive impairment…). In 2012, Gondi reported that a dose given to 40% of the bilateral hippocampi greater than 7.3 Gy is associated with long-term impairment in list-learning delayed recall after FSRT for benign or low-grade adult brain tumors. There is no published or recruiting prospective study evaluating the impact of proton-therapy or conventional irradiation on neurocognitive function for meningioma patients. Notably, long-term cognitive or ocular impact of these modern irradiation schemes remains poorly known. Yet, these patients had a long life-expectancy, and are at risk of developing long-term sequelae. Thus, according to its ballistic advantage, an improvement of patient functional outcomes and a reduction of neurocognitive long-term toxicity are expected if tissue sparing proton-therapy is used. In this context, a randomized prospective study, evaluating long-term toxicity of these two irradiation modalities (Proton Therapy (PRT) and photon radiotherapy (XRT)) seems crucial to further assess proton-therapy indication for these patients. Although literature reports excellent outcomes for intracranial meningioma patients treated by proton-therapy, none of the eight retrospective studies found in the literature used an accurate and full evaluation of long-term toxicity