Neurocognitive Impact of Whole Brain Radiation on Patients With Brain Metastases: Secondary Analysis of RTOG BR-0018

[Cognitive evaluation during brain radiotherapy in adults: a simple assessment is possible]

Brain irradiation can be used for the treatment of cancers in different protocols: focal radiotherapy, whole brain radiotherapy, with or without additive dose on the tumour. Different modalities (conformational, stereotactic radiosurgery) can be used for curative or prophylactic treatment. Brain radiotherapy leads to cognitive deterioration with subcortical profile. This cognitive deterioration can be associated to radiation-induced leukoencephalopathy on brain MRI. Taking into account radiation induced cognitive troubles is becoming more important with the prolonged survival allowed by treatment improvement. Concerning low-grade gliomas, radiation-induced cognitive troubles appear about 6 years after treatment and occur earlier when the fraction dose is important. Primitive cerebral lymphoma treatment can induce cognitive troubles in 25 to 30% surviving patients. These deficits are more frequent in elderly patients, leading to radiotherapy delay in those patients. Patients treated for brain metastasis often have cognitive impairment before radiotherapy (until 66%), this pretreatment impairment is related to global survival. The use of conformational radiation therapy, particularly with hippocampal sparing is conceptually interesting but has not proved its efficiency for cognitive preservation in clinical trials yet. Stereotactic radiation therapy could be an interesting compromise between metastatic tumoral volume reduction and cognitive preservation. Taking care of radiotherapy induced cognitive troubles is a challenge. Before considering its treatment and prevention, we need to elaborate a way of detecting them using a reliable and easy way. CSCT, a computerized test whose execution needs 90 seconds, could be used before treatment and during the clinical follow-up by the patient's oncologist or radiotherapist. If the patient's performance reduces, he can be oriented to a neurologist in order to perform fuller evaluation of its cognitive capacities and be treated if necessary.

Neuropsychological testing and biomarkers in the management of brain metastases

Prognosis for patients with brain metastasis remains poor. Whole brain radiation therapy is the conventional treatment option; it can improve neurological symptoms, prevent and improve tumor associated neurocognitive decline, and prevents death from neurologic causes. In addition to whole brain radiation therapy, stereotactic radiosurgery, neurosurgery and chemotherapy also are used in the management of brain metastases. Radiosensitizers are now currently being investigated as potential treatment options. All of these treatment modalities carry a risk of central nervous system (CNS) toxicity that can lead to neurocognitive impairment in long term survivors. Neuropsychological testing and biomarkers are potential ways of measuring and better understanding CNS toxicity. These tools may help optimize current therapies and develop new treatments for these patients. This article will review the current management of brain metastases, summarize the data on the CNS effects associated with brain metastases and whole brain radiation therapy in these patients, discuss the use of neuropsychological tests as outcome measures in clinical trials evaluating treatments for brain metastases, and give an overview of the potential of biomarker development in brain metastases research.