Literature Review: Cognitive Function After Radiotherapy For Pediatric Low-grade Gliomas In Clinical Research

Pediatric low-grade gliomas are common brain tumors, which occur mainly in children aged 5 to 9 years and account for 30%-50% of central nervous system tumors. The patients often present generalizing symptoms included headaches, nausea, vomiting and lethargy, which are due to increased intracranial pressure. They also present focal neurological symptoms, seizures and endocrinopathies. The diagnosis of low-grade gliomas mainly depends on imaging examinations such as CT scan and magnetic resonance imaging(MRI), surgical biopsy and molecular diagnosis, and share similar performance on neuroimaging. The treatment measures of pediatric low-grade gliomas include observation, follow-up, surgery, radiation, chemotherapy and a combined option. Moreover, the children of low-grade gliomas usually have relatively favourable prognosis and prolonged survival, with a progression-free survival rate of 60%-85%. It often appears long-term cognitive dysfunction in the children after radiotherapy and so can be helpful for predicting prognosis. Brain injures caused by changes of white matter, neurogenesis, plasticity and cognitive brain anatomical structures seem to be associated with neurocognitive deficit. It requires people to choose sensitive cognitive function testings according to the multiple evaluations, such as attention, executive function, memory, language, information processing speed. The tests of pediatric cognitive function comprise Child Behavior Checklist, Wecbsler Intelligence Scale for Children, California Verbal Learning Test-Children’s Version and Visual-Auditory Learning test, which can describe the pattern of disablities including the falling of IQ and academic achievement. Radiotherapy is one of the most common treatments to childhood cancer, which has three parameters: radiation dose, volume and age at time of treatment. The results showed that under the level of conformal radiotherapy local radiotherapy with standard dose is not the main risk factor of cognitive dysfunction. However, chemotherapy, survival time, hydrocephalus, shunt insertion, seizure, antiepileptic drugs, endocrinopathies and steroids also impair the cognitive function. Because of the lacking specificity of imaging, the diagnosis of radiation-induced cognitive decline should correlate with these clinical syndrome and pathology. Cognitive function may affect the long-term survivors that contain independent living, social function, profession, mood and health-related quality of life. Therefore, it is necessary to take some measures. Depending on the level of cognitive deficit and complications, there are several medical interventions, such as donepezil, methylphenidate, gingko biloba and armodafinil. In addition, the potential benefit of innovative radiotherapy technologies including intensity-modulated radiotherapy, hyperfractionated radiotherapy and proton therapy can reduce the risk of cognitive dysfunction, as well as hippocampal avoidance. What’s more, rehabilitation, physical exercise, learning, school continuation and psychological support are also the significant adjuvant therapy. For younger pediatric patients with low-grade gliomas, chemotherapy is chosen as the first-line treatment to reduce the risks, which radiotherapy should be avoid or delayed.