See the separate Brain Tumours in Children article.
Brain tumours cannot truly be differentiated into benign or malignant. 'Benign' tumours account for significant morbidity and mortality, as they can continue to grow and cause the adverse effects of any space-occupying lesion. Therefore, the preferred terms are 'high-grade tumour' (a tumour that grows rapidly and is aggressive) and 'low-grade tumour' (a tumour that grows slowly but which may or may not be successfully treated).
- Primary brain tumours represent about 2% of all tumours diagnosed in the UK. It has been estimated that the lifetime risk of developing brain and other central nervous system (CNS) cancer is 1 in 77 for men and women in the UK. The incidence of brain and CNS tumours in the UK in 2011 was 13.2 per 100,000 for males and 12 per 100,000 for females.
- The incidence rates for brain and CNS cancers in the UK increased slightly between 1975 and 2011. Some specific types of brain tumours are significantly increasing in incidence - eg, gliomas in the elderly and lymphomas.
- There are more intracranial tumours reported in Africa, Japan and the Far East.
- The incidence of primary CNS lymphomas is 4-5 per 1,000 population among patients with AIDS and 0.3 per 100,000 in the immunocompetent population. The incidence of primary CNS lymphomas has increased in recent decades.
- In adults, most brain tumours are supratentorial and high-grade gliomas and meningiomas predominate. Brain tumours can develop at any age in adults but are most common in people aged between 50 and 70.
- Primary tumours of the brain are more common among more affluent groups but the reverse trend occurs for brain metastases.
- Ionising radiation.
- Vinyl chloride is associated with high-grade gliomas.
- Immunosuppression (eg, as a result of AIDS) may cause cerebral lymphoma.
- Possible increased risk with oil refining, embalming and 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 are needed[3, 4].
- Inherited syndromes with an increased risk of brain tumours include neurofibromatosis, von Hippel-Lindau disease, tuberous sclerosis, Li-Fraumeni syndrome, Cowden's disease, Turcot's syndrome and naevoid basal cell carcinoma syndrome (Gorlin's syndrome).
Histological types of brain tumour
Metastases from other cancers are the most common intracranial tumours in adults, and are 10 times more common than primary tumours. The main histological types of brain tumours include:
- Gliomas and glioblastoma multiforme.
- Primary cerebral lymphomas.
- Common malignancies spreading to the brain include lung cancer, breast cancer, stomach cancer, prostate cancer, thyroid cancer, colorectal cancer, melanoma and kidney cancer.
Anyone presenting with new, unexplained headaches or neurological symptoms needs a thorough neurological history and examination. The presentation will depend on location and rate of growth but includes features of a space-occupying lesion and raised intracranial pressure (ICP) (see links for separate articles):
- Headache, which is typically worse in the mornings.
- Nausea and vomiting.
- Progressive focal neurological deficits - eg, diplopia associated with a cranial nerve defect, visual field defect, neurological deficits affecting the upper and/or lower limb.
- Cognitive or behavioural symptoms.
- Symptoms relating to location of mass - eg, frontal lobe lesions associated with personality changes, disinhibition and parietal lobe lesions might be associated with dysarthria.
- Papilloedema (absence of papilloedema does not exclude a brain tumour).
- Other causes of a space-occupying lesion.
- Cerebrovascular event.
- Idiopathic intracranial hypertension.
- Blood tests may be useful in determining any complications of the tumour (eg, bleeding disorders, hypercalcaemia or inappropriate antidiuretic hormone secretion) or in the initial assessment of other possible causes of headache (eg, ESR and CRP as indicators of possible giant cell arteritis).
- Diagnosis largely rests on brain imaging - eg, 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 - eg, germ cell tumours and lymphoma.
- Technetium brain scan: is useful in the diagnosis of destructive skull vault (eg, metastases) and skull base lesions.
- Imaging using labelled amino acid analogues may be indicated for detection of viable tumour tissue, tumour delineation, selecting the best biopsy site and planning therapy.
- Magnetic resonance angiography (MRA) and magnetic resonance spectroscopy (MRS) are occasionally used to define changing size or blood supply. Positron emission tomography (PET) is helpful in grading gliomas or locating an occult primary.
- Biopsy and tumour removal: stereotactic biopsy via a skull burr-hole to obtain histology of a suspected malignancy. Open exploration (craniotomy) may be required - eg, for a symptomatic meningioma.
There is no standard staging system for brain tumours. Brain tumours can spread to other parts of the brain and the spinal cord - but distant metastases are rare.
See also the separate Rising Intracranial Pressure article.
- Tumours should be resected whenever possible. 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 where there is infiltration of local normal brain tissue.
- Surgery should also be considered to reduce mass effect and treat hydrocephalus in order to provide symptomatic relief.
- If surgery is not an option then radiotherapy should be considered.
Photodynamic therapy can be carried out at the same time as surgical resection. A photosensitising agent is injected (usually intravenously, sometimes by direct injection into the tumour). The photosensitising agent is activated by illuminating the selected area with a laser source. Because of limited evidence of efficacy and safety, this procedure is not currently recommended by the National Institute for Health and Care Excellence (NICE) for routine patient care.
- External beam radiotherapy can be curative for many patients and also prolongs survival.
- For some types of tumours, it is the treatment of choice - eg, metastatic brain tumours, leptomeningeal metastases.
- Whole brain radiation is used with some tumours - eg, medulloblastomas, primary CNS lymphomas. An alternative technique is 'involved-field radiation', which means that normal brain tissue is exposed to less radiation.
- In stereotactic radiosurgery, focal radiotherapy is administered to a target, thus avoiding exposure to normal brain tissue.
- 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 - eg, temozolomide in glioblastoma multiforme, nitrosureas in oligodendrogliomas, platinum agents in medulloblastomas[6, 8].
Other therapeutic agents
- Patients may also require analgesics, anticonvulsants, anticoagulants and corticosteroids.
- Corticosteroids help to reduce mass effect of raised ICP.
Treatment of brain metastases
- Corticosteroids should be used if cerebral oedema is present.
- Surgery may be an option for patients with three or fewer brain metastases - provided the primary is controlled. This is associated with improved survival.
- For metastases that are 3-3.5 cm 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.
See the separate Palliative Care, Pain Control in Palliative Care, Nausea and Vomiting in Palliative Care, Prescribing in Palliative Care, End of Life Care, Looking After People With Cancer and Helping Patients Face Death and Dying articles.
- Acute haemorrhage into a tumour.
- Blockage of cerebrospinal fluid outflow, causing hydrocephalus. Sudden death may occur as a result of obstruction of outflow drainage from the third ventricle.
- Sudden increases in ICP may lead to life-threatening brain herniation through the foramen magnum or transtentorial foramina.
- Complications of radiotherapy: acute toxicity is rare with modern schedules but subacute or chronic effects may occur:
- Subacute encephalopathy with somnolence and headaches may occur 6-16 weeks after radiation therapy.
- Prolonged radiation treatment may lead to impairment of intellectual capacity.
- 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 the third most common cause in adolescents and young adults (up to the age of 34).
Further reading and references
; NICE Guideline (July 2018)
; Cancer Research UK
; Primary brain tumours in adults. Lancet. 2003 Jan 25361(9354):323-31.
; Does the use of cell phones cause brain tumors? Clin J Oncol Nurs. 2008 Aug12(4):671-2.
; Meta-analysis of long-term mobile phone use and the association with brain tumours. Int J Oncol. 2008 May32(5):1097-103.
; NICE Clinical Guideline (2015 - last updated July 2017)
; Central nervous system tumors. Mayo Clin Proc. 2007 Oct82(10):1271-86.
; NICE Interventional Procedure Guidance, March 2009
; NICE Technology Appraisal Guidance, June 2007
; European Federation of Neurological Societies (2006)
; Survival from brain tumours in England and Wales up to 2001. Br J Cancer. 2008 Sep 2399 Suppl 1:S102-3.