Brain Tumours in Adults

See related articles: Space Occupying Lesions, Brain Tumours in Children and under individual tumour types.

Brain tumours can be classified as malignant or benign and malignant tumours can be primary or secondaries. Brain metastases are the commonest intracranial tumour of adults - being 10 times more common than primary tumours. Secondaries most commonly arise in association with lung malignancy, breast malignancy, melanoma and colo-rectal malignancy.

Benign tumours also account for significant morbidity and mortality as they can continue to grow and cause adverse effects like all space occupying lesions.

• In UK - a total of 13,000 brain tumours are diagnosed per year of which it is estimated that 4,500 are primary brain tumours (300 of which are in children). Thus it represents about 1.6% of all tumours diagnosed in the UK.^1,2
• In US - there is an incidence of about 15 per 100,000 person years for all brain tumours (half of which are benign).³
• Incidence is marginally higher in women which may result from the higher incidence of meningiomas in women.

Genetic factors

• Genetic predisposition - uncommon
• Gliomas inherited in several familial diseases e.g. type 1 neurofibromatosis, Gorlin syndrome, Li Fraumeni syndrome³

Environmental factors

• Vinyl chloride - associated with high grade gliomas.
• Ionizing radiation.
• HIV - increased risk of primary lymphoma.
• Possible increased risk with oil refining, embalming, textiles but these need further investigation.
• Mobile phone use - no definite link has been discovered between mobile phone use and brain tumours; however further data is needed.^4,5

Symptoms and signs relate to tumours being a space occupying lesion (see our record, link above). Some of the significant features are outlined here.

Symptoms include

• Headache - worse in morning
• Nausea and vomiting
• Seizures
• Drowsiness - in later stages
• Symptoms relating to location of mass e.g. frontal lobe lesions associated with personality changes, disinhibition and parietal lobe lesions might be associated with dysarthria

Signs include

• Examination may be completely normal
• Focal neurological deficits e.g. diplopia, weakness
• Papilloedema - remember the lack of this sign does not exclude a brain tumour

As for space occupying lesion and includes intracranial abscess or cerebrovascular event.

• Blood tests may not reveal any abnormalities.
• Diagnosis largely rests on brain imaging e.g. CT scan and/or MRI scan (both with or without contrast). MRI is more sensitive. The spine may also need to be imaged especially in CNS tumours that spread to the spine e.g. germ cell tumours and lymphoma.³
• Definitive diagnosis will require tissue and this needs to be reviewed by experienced neuropathologists.

Patients should be referred to specialists and if possible brain imaging should be organised (see guidance on referral).⁶ Any cases where there is concern for the patient e.g. worsening confusion, change in vision then discuss with local specialist. The following box gives a summary of referring patients:

Surgery

• Tumours should be resected where possible and this is usually curative in benign tumours and less so in malignant tumours.
• Surgery will also provide tissue for a formal diagnosis.
• Surgery may not be a viable option especially if the tumour is located in a region associated with critical function or there is infiltration of local matter.
• Surgery should also be considered to reduce mass effect and treat hydrocephalus and thus provide symptomatic relief.
• If surgery is not an option then radiotherapy should be considered.

Radiation

• External beam radiotherapy can be curative for many patients and also prolongs survival.
• For some types of tumours it is the treatment of choice e.g. metastatic brain tumours, leptomeningeal metastases.
• Whole brain radiation is used with some tumours e.g. medulloblastomas, primary CNS lymphomas. An alternative technique is "involved-field radiation" which means that normal brain tissue is exposed to less radiation.³
• In stereotactic radiosurgery focal radiotherapy is administered to a target thus avoiding exposure to normal brain tissue.

Chemotherapy

• The role of chemotherapy in brain tumours is not as marked as in other tumours (except for CNS lymphoma which requires aggressive intrathecal and intravenous chemotherapy).
• It does provide modest benefit and is important in palliative care and as an adjunct to combined surgery and radiotherapy.
• Commonly used agents include those that can cross the blood brain barrier e.g. temozolomide in gliomas, nitrosureas in oligodendrogliomas, platinum agents in medulloblastomas.^3,7

Other therapeutic agents

• Patients may also require analgesics, anticonvulsants, anticoagulants and corticosteroids.
• Corticosteroids help to reduce mass effect and intracranial pressure.

• Corticosteroids should be used if cerebral oedema is present.
• Surgery may be an option for patients with 3 or less brain metastases - provided the primary is controlled. This is associated with improved survival.
• For metastases that are 3-3.5cm in size stereotactic radiosurgery may be an option.
• Whole-brain radiotherapy can be given after surgery or radiosurgery. However, it is currently debated whether it should be given early or late in the illness.
• Whole-brain radiotherapy is the only treatment modality for those who are not suitable for surgery or radiosurgery.
• Chemotherapy should be considered if the brain secondaries arise from a primary chemosensitive tumour.

• Brain tumours, both benign and malignant, are associated with morbidity relating to mass effect if they continue to increase in size.
• Malignant brain tumours are the leading cause of death from solid tumours in children and third common cause in adolescents and young adults (up to the age of 34).