Radiation Dose–Volume Effects in the Brain

Abstract

We have reviewed the published data regarding radiotherapy (RT)-induced brain injury. Radiation necrosis appears a median of 1–2 years after RT; however, cognitive decline develops over many years. The incidence and severity is dose and volume dependent and can also be increased by chemotherapy, age, diabetes, and spatial factors. For fractionated RT with a fraction size of <2.5 Gy, an incidence of radiation necrosis of 5% and 10% is predicted to occur at a biologically effective dose of 120 Gy (range, 100–140) and 150 Gy (range, 140–170), respectively. For twice-daily fractionation, a steep increase in toxicity appears to occur when the biologically effective dose is >80 Gy. For large fraction sizes (≥2.5 Gy), the incidence and severity of toxicity is unpredictable. For single fraction radiosurgery, a clear correlation has been demonstrated between the target size and the risk of adverse events. Substantial variation among different centers’ reported outcomes have prevented us from making toxicity–risk predictions. Cognitive dysfunction in children is largely seen for whole brain doses of ≥18 Gy. No substantial evidence has shown that RT induces irreversible cognitive decline in adults within 4 years of RT.

Manejo del cáncer de cabeza y cuello: ¿Radioterapia a quién, cuándo y por qué?

“…Complicación 2ria a RT Criterios QUANTEC Sistema nervioso central -Leucoencefalopatía por daño en la sustancia >2,5 Gy por fracción : 5% radionecrosis blanca para dosis total 80-150 Gy -Necrosis* Niños con RT holocraneal a dosis total ≥18 Gy -Pérdida de sustancia gris produce deterioro cognitivo (38) RT asociada a cirugía -Gran calibre: estallido carotideo.…”

Optimal management of elderly patients with glioblastoma

“…9,10 The risk and degree of radiation-related neurotoxicity has also been noted to increase with age. 11,12 Lawrence and colleagues from the Radiation Therapy Oncology Group (RTOG) performed a retrospective review of neurotoxicity of acute and late grade  3 neurotoxicity in 2,761 patients from 14 prior RTOG trials in high-grade gliomas from 1983 to 2003. All patients had received either chemotherapy (83%) or a biologic agent (17%) during RT (median dose 60 Gy).…”

Quality of Life of Nasopharyngeal Cancer Survivors in China

“…Today, quantitative correlates of dose-volume with clinical outcome can obtained because of the use of three-dimensional treatment planning. The quantec (quantitative analysis of normal tissue effects in clinic) articles [22][23][24][25] summarized studies since the early 1990s and updated the information provided by Emami et al The dose-volume limits of major organs at risk during treatment for npc as recommended by quantec are these:…”