Brain Imaging to Predict Toxicity in Elderly Patients After Radiotherapy

The investigators' aim with the BRITER study is to produce a way of predicting who might be more or less likely to suffer side effects from radiotherapy prior to starting treatment for a glioblastoma (GBM), a type of brain tumour. GBM is the commonest primary malignant brain tumour. Treatment options include chemotherapy, radiotherapy or best supportive care. The focus should be on maintaining a good quality of life for as long as possible. Radiotherapy to the brain is an effective treatment, however it can produce side effects. The degree of side effects different patients experience can vary widely. It has been thought that if the patient's underlying normal brain is fragile due to an underlying mild dementia or problems associated with high blood pressure or cholesterol then this might make them more vulnerable to radiotherapy. MRI scans can be used to assess whether there are changes in the normal brain. The BRITER study aims to use MRI scans to see whether the investigators can predict those patients who might be more at risk of side effects from radiotherapy. The trial is aimed at patients aged \> 65 who have been newly diagnosed with a GBM and are going to receive radiotherapy. Patients who agree to take part in the trial will have had an MRI scan as part of their normal diagnosis. Participants will undertake some questionnaires before starting their radiotherapy which will aim to assess their quality of life and their mental processes of perception, memory, judgment, and reasoning (called cognitive function). Participants may also need an extra MRI scan. Participants will repeat these questionnaires 4 and 8 weeks after treatment when they come for their follow up appointments. The investigators will compare them to measurements made on the pre-treatment MRI scan. Participation in the study does not change the treatment the patient receives. The investigators hope that the BRITER study will enable them to predict the degree of side effects a patient is likely to experience before embarking on radiotherapy treatment. This will enable more informative, individualised discussions surrounding the best treatment path for older patients with a GBM.