8th August 2024

Primary and metastatic tumours

Brain tumours are the ninth most common neoplasm diagnosed in the UK and the second most common in children. The majority of primary brain tumours arise from the meninges and the most common of these by far are meningiomas, which are more common in women and likely to be benign.

Malignant brain tumours primarily arise from neuroepithelial tissue and are generally termed gliomas. The most common of these in adults is glioblastoma multiforme (GBM), a highly aggressive tumour of astrocyte origin. Their incidence is similar in men and women and is associated with advancing age. Less aggressive tumours (low-grade gliomas) are more common in children and young people and carry a better prognosis.

Other primary brain tumours include pituitary adenomas, haemangiomas, nerve sheath tumours, such as vestibular Schwannoma, and primary CNS lymphoma. When considering brain tumours, it is especially important to consider metastatic disease – metastatic deposits in the brain are significantly more common than primary brain tumours. Typical primary sites are: lung, breast, kidney, lower GI tract, and skin.

Investigation and management

Initial diagnosis is with contrast CT brain, though the preferred form of imaging is MRI with gadolinium contrast for better resolution and ability to identify tissue types. If metastatic disease is suspected, staging CT imaging should be arranged. If there are no concerns about raised intracranial pressure, and especially if there is concern of a CNS lymphoma (e.g. in the patient with HIV), a lumbar puncture should be performed for flow cytometry.

Management should be led by neurosurgical and oncology teams, but, in general, for lesions with mass effect and surrounding oedema, high-dose steroids should be given, unless there is a suspicion for CNS lymphoma. In this case, steroids should ideally be withheld until a tissue diagnosis is obtained. If the presentation was with seizures, anti-seizure medication should be started.

General principles for ongoing management are usually combination therapy – surgical resection, radiotherapy (including radiosurgery, e.g. Gamma Knife), and chemotherapy in select cases (temozolomide is standard for GBM).

Spinal cord lesions

These are relatively infrequently encountered compared to other CNS tumours but are an important cause of focal neurology, typically in conjunction with unremitting back pain. They are classified as intramedullary (within the substance of the cord), intradural but extramedullary (such as meningiomas or nerve sheath tumours), and extradural (usually metastases).

Like brain tumours, the majority of intramedullary spinal cord tumours are gliomas, with ependymomas predominating. Intradural but extramedullary lesions are most frequently meningiomas, but approximately a quarter are nerve sheath tumours – either Schwannomas or neurofibromas. Extradural lesions most frequently occur within the vertebral bodies and are most commonly caused by metastatic disease, typically from a breast, lung or prostate primary. They classically manifest with spinal cord or cauda equina compression but can cause intradural invasion.

Investigation of spinal cord lesions is primarily via MRI or CT myelogram for those unable to undergo MRI scanning. Management is usually a combination of surgery and radiotherapy.