This guideline covers diagnosing, monitoring and managing any type of primary brain tumour or brain metastases in people aged 16 or over. It aims to improve diagnosis and care, including standardising the care people have, how information and support are provided, and palliative care. In January 2021, we replaced our recommendation on surgical cavity radiosurgery and radiotherapy with a link to the NHS England commissioning policy on stereotactic radiosurgery and stereotactic radiotherapy to the surgical cavity following resection of cerebral metastases.