About brain tumours
A brain tumour is a collection of abnormal cells growing in or around the brain. Specific causes of brain tumours remain elusive - hence the importance of banks like the Alfred Brain Bio-databank in furthering medical research.
There are multiple different types of brain tumours. A brain tumour may be a primary or secondary. Primary brain tumours originate in or next to the brain. Most common adult primary brain tumours are meningiomas, pituitary tumours and gliomas such as astrocytoma and glioblastoma (GBM).
Tumours in other parts of the body are often classified as benign or malignant. These terms are not used in the official classification of brain tumours. Brain tumours are instead graded based on the histological characteristics of the tumour (how the tissue looks under a microscope). Nevertheless, the term “benign” is often used to describe some brain tumours such as meningiomas and pituitary tumours because these tumours usually have a well-defined border, do not spread to distant sites via the bloodstream, and treatment is usually curative. On the other hand, the terms benign and malignant are not used to describe gliomas. Some gliomas are very slow-growing but spread through the brain – these are termed “low grade”. Rapidly-growing gliomas are called “high grade”.
The World Health Organization (WHO) classification of central nervous system (CNS) tumours is the most widely accepted system to grade primary brain tumours. The grades predict prognosis and help determine treatment of that tumour type.
Secondary brain tumours or metastasis are tumours that have spread to the brain. Secondary brain tumours are classified as malignant because they started as cancer elsewhere in the body. For example, metastatic lung cancer began as cancer in the lung which has spread to the brain. The most common cancers to spread to the brain are melanoma, lung, breast, kidney and bowel.
Grades of primary brain tumours
- Slow-growing and usually associated with long-term survival
- Unlikely to spread to other parts of the brain
- Well defined and contained edges
- Treated with surgery or radiotherapy alone, this treatment is usually curative
- Often referred to as “low grade”
- Relatively slow-growing cells
- Can invade adjacent normal tissue
- The tumour can progress to become a higher-grade tumour
- Treatment tailored to individual patients – may include close observation, surgery, radiotherapy, chemotherapy, or a combination of these
- Often referred to as “anaplastic”
- Actively reproducing abnormal-looking cells
- Invade adjacent normal brain tissue
- Tumour tend to grow more quickly than Grade II tumours
- Treatment usually multimodality - combination of surgery, radiotherapy, and chemotherapy
- Fast- growing
- Poorer prognosis
- Very abnormal appearance under a microscope
- Treated in a multimodality fashion
Patients with brain tumours may present for healthcare with a variety of signs and symptoms. Symptoms may be associated with the location, size and type of tumour. The most frequent clinical presentations include seizure, headache, nausea and vomiting, arm or leg weakness, visual problems, speech difficulty and confusion.
Imaging (brain scans)
The two main types of imaging (brain scans) used in people with brain tumours are computed tomography (CT) and magnetic resonance imaging (MRI). When a person has symptoms that could be caused by a brain tumour, the first scan performed is usually a CT. If an abnormality is seen, an MRI scan will usually be performed as part of the diagnostic work up. Brain scans cannot provide a definitive diagnosis of a brain tumour.
Reasons for doing imaging in the management of brain tumours include:
- To provide a radiological diagnosis of a presumed brain tumour
- To see where the tumour is within the brain
- To see what effects the tumour is having on the surrounding brain
- For treatment planning and management
- To assess whether treatment has been successful (for example to see if tumour has been left behind after surgery)
- To check for complications caused by treatment
- To check for tumour growth or changes after treatment.
There is no ‘one-size-fits-all’ treatment for brain tumours. Treatment decisions will be made together with the patient and multidisciplinary team which includes neurosurgeons, radiation oncologists, medical oncologists, and other specialists. Treatment used for brain tumours is based on many factors including overall health, location, size and type of tumour. Your doctors today also base treatment decisions on the genetics of your tumour.
Treatment may include surgery, radiotherapy and medical therapy such as chemotherapy, or a combination of these treatments. Tumours of grade two or higher usually require a combination of these therapies. For higher grade tumours, treatment may be concurrent (given at the same time) or following each other in quick succession. Steroids are also used to control swelling in the brain around the tumour.
Surgery is usually the first treatment used for a brain tumour. Sometimes surgery is not safe because the tumour is too close to important areas of healthy brain. For Grade 1 tumours complete removal may be the only treatment required. For Grade 2-4 tumours, surgery alone is rarely sufficient.
Aims of surgery include:
- To remove as much of the tumour as possible, whilst minimising damage to surrounding healthy brain
- To provide a sample for examination by the neuropathologist, to confirm diagnosis
- To reduce the amount of tumour to be treated with radiotherapy and chemotherapy.
Radiation can destroy tumour cells or delay tumour growth. For some Grade 1 tumours, radiotherapy alone may be sufficient to permanently halt tumour growth. For high-grade tumours, radiotherapy starts within a few weeks of diagnosis.
Chemotherapy is the use of drugs to kill cancer cells. The goals of chemotherapy are to destroy the cancer cells left after surgery and slow tumour growth by hindering the cancer cells’ ability to grow and divide. Chemotherapy is typically given after surgery and may be given alone or combined with radiotherapy.
Cure Brain Cancer Foundation
About Brain Cancer
The Brain Tumour Charity
How brain tumours are graded
Australian Institute of Health and Welfare
Brain and other central nervous system cancers
National Brain Tumour Society
The 2016 World Health Organization Classification of Tumors of the Central Nervous System: A Summary