Neurovisual outcome following proton radiation therapy

Visual complications of proton beam therapy for clival chordoma

“…5 Yet in all of our cases, either hypertension, postradiation hypopituitarism, or collagen vascular disease was present. None had chemotherapy.…”

“…In all, 52 clinically documented cases over 20 years following external fractionated radiotherapy were found in the literature by Habrand. 5 The risk of developing radiation optic neuropathy was estimated at about 5-10%, highest in the first 2 years but ranging from 2 months up to 8 years. 5 Proton beam therapy gained interest in the 1980s because the proton 'Bragg peak' allowed a rapid reduction in dose distal to the target with a sharply defined lateral beam edge.…”

“…5 The risk of developing radiation optic neuropathy was estimated at about 5-10%, highest in the first 2 years but ranging from 2 months up to 8 years. 5 Proton beam therapy gained interest in the 1980s because the proton 'Bragg peak' allowed a rapid reduction in dose distal to the target with a sharply defined lateral beam edge. Delivery of high doses of radiotherapy to residual tumour was reported possible with sparing of adjacent neurological structures.…”

“…Delivery of high doses of radiotherapy to residual tumour was reported possible with sparing of adjacent neurological structures. [5][6][7] Proton energy deposition shows a shift towards higher lineal energy for proton beams relative to cobalt-60 gamma rays, leading to a slightly elevated biological response. The relative biological effectiveness of protons to photons is 1.1.…”

“…6 Neurovisual outcome was soon reported in 15 patients treated with a tumour of the upper clivus and followed up over 30-68 months. 5 Doses of radiation received were estimated using a dose-volume histogram. When a fifth or more of the optic nerve was exposed to 60 CGE, a 22% complication rate was estimated.…”