An observational study of neurocognitive function in patients undergoing stereotactic radiosurgery at Velindre Cancer Centre

Radiation treatment for brain metastases has traditionally involved whole brain radiotherapy (WBRT). Technical developments now allow radiotherapy to be targeted precisely to small areas of cancer within the brain using... [ view full abstract ]

Radiation treatment for brain metastases has traditionally involved whole brain radiotherapy (WBRT). Technical developments now allow radiotherapy to be targeted precisely to small areas of cancer within the brain using stereotactic radiosurgery (SRS). Combining WBRT and SRS improves survival compared with WBRT alone. WBRT has significant side effects particularly on short and long term memory and even with SRS treatment alone recent studies have demonstrated that around half of patients suffer memory impairment. Certain areas of the brain, such as the hippocampus, are considered particularly sensitive to radiotherapy but the mechanism for memory impairment is unknown. Hypotheses include changes in structure, cerebral blood flow and brain connectivity. Equally, radiotherapy tolerance doses for the hippocampus and other structures within the brain important for memory are not well defined. We have obtained funding and ethical approval to conduct a prospective observational study in collaboration with the Cardiff University Brain Research Imaging Centre (CUBRIC). In this study we aim to recruit 40 patients undergoing SRS treatment over 18 months and we will correlate data from neurocognitive function (NCF) tests with radiation dosimetry to cognitive structures and with detailed MRI scans using latest MRI techniques. Detailed NCF assessments, according to the RANO group recommendations, will be conducted before and after SRS treatment. MRI brain scans using a combination of functional structural, spectroscopic and microstructural MRI scans will be performed before and after SRS. Radiotherapy doses received by brain structures important for memory including the hippocampus, amygdala, prefrontal cortex and limbic system will be calculated and correlated with NCF and MRI assessments. We predict that by correlating this information we will obtain important new insights into radiotherapy effects on memory and on the radiotherapy tolerance doses for these crucial structures when delivering SRS.