Brain Tumours

There are numerous types of brain tumours and they all behave differently and so require different combinations of treatment. Following is a brief account of the more commonly encountered tumours and our current thoughts on treatment.

Basic definitions

• Tumour - abnormal growth of cells. The word tumour is not synonymous with cancer.
• Benign - slow growing tumour that usually does not infiltrate and spread and so can be controlled well.
• Malignant - rapidly growing, aggressive tumour that does infiltrate and spread and so is difficult to control.
• Primary Tumour - A tumour that arises from the tissue of the affected organ.
• Secondary (Metastatic) Tumour - A tumour that has arisen from a distant site and spread to the affected organ.

Gliomas

Gliomas are primary brain tumours. They arise from the supporting cells of the brain. The two main types of gliomas are Astrocytomas and Oligodendrogliomas.

What causes gliomas?

We don't know.

Radiation exposure can give rise to these tumours. However the vast majority of patients who have gliomas have never had significant radiation exposure. There is some debate at present about the effect of mobile phones. We do not have firm evidence as yet.

Some people with certain genetic conditions also develop gliomas.

Astrocytomas

These tumours arise from cells called astrocytes which are found within the brain and mostly within the substance called "white matter". These tumours are rarely discrete lumps. They often display tentacles of tumour that can infiltrate the brain.

They can arise as a slow growing variety or a malignant form. In order to differentiate the types, we have a grading system based on what the tumour cells and tissue look like under a microscope.

• Grade I - Pilocytic astrocytoma. Mostly benign tumours that occur almost exclusively in children and young adults.
• Grade II - Low grade astrocytoma. Average age at diagnosis is 35 years. Slow growing tumour. These tumours can progress to a more malignant form after some years.
• Grade III - Anaplastic astrocytoma. Average age at diagnosis is 45 years. Faster growing than grade IIs. These tumours usually progress to a grade IV within a few years.
• Grade IV - Glioblastoma Multiforme (GBM). Very aggressive, fast growing malignant tumour. Average age at diagnosis is 55 years. GBMs often arise from low grade astrocytomas but may also spontaneously arise as a GBM.

What is the current recommended treatment Astrocytomas?

Pilocytic Astrocytomas (grade I) can often be cured by surgery alone.

On the other hand, at the present time there is no known cure for Grade II-IV astrocytomas.

Treatment is therefore aimed at controlling the tumour for as long as possible. There are three established "control" methods as present.

• Surgery
• Radiotherapy
• Chemotherapy

Each of these treatments is administered by a different specialist. Ideally, these specialists should work together at the same hospital as a team so as to provide integrated care for the patient.

Surgery

Surgery for these brain tumours should ideally be performed by someone who subspecialises in the field of Neuro oncology and is part of a multidisciplinary team as described above.

Surgery is required in some form for all of these tumours.

Biopsy

Surgery may just be to obtain some tissue to make a firm diagnosis. This is called a biopsy. It still requires a general anaesthetic and is usually performed through a small drill hole in the skull called a "burr Hole". In order to locate the tumour, a technique known as stereotaxy is utilized. A needle is then passed through brain into the tumour to obtain some tissue. This tissue sample will then be analysed by a Pathologist to determine the exact diagnosis. Occasionally, the tissue obtained may not be of adequate quality to be analysed correctly. In this instance, further surgery may be required to obtain more tissue of better quality.

Surgery for radical resection

Surgery may also be performed to remove as much of the tumour as possible. There is a good amount of medical evidence that states that radical surgery has the effect of lengthening survival. The aim of radical surgery is to remove greater than 95% of the tumour seen on the MRI scan.

Radical surgery may not always be possible. It really depends on where exactly the tumour is located as to whether it can be achieved. Radical surgery is high risk surgery.

Radical surgery has become safer because of technological developments. The three most important technological adjuncts to surgery are the operating microscope, stereotactic navigation and the intraoperative MRI. The former two are found in all hospitals that offer Neurosurgery and are considered standard of care. The intraoprative MRI is unique to Royal Prince Alfred Hospital. Known as the "Brain Suite", it is the only one of its kind in Australia and one of 25 worldwide units.

Click here for more information

Radiotherapy

Radiotherapy is administered by a specialist known as a Radiation Oncologist.

Radiotherapy is the crucial next step after surgery for Grade III and Grade IV astrocytomas. The need for radiotherapy for grade II astrocytomas is more controversial. It appears to delay recurrence and transformation into a grade III but does not seem to lengthen overall survival.

Chemotherapy

Chemotherapy is used in conjunction with radiotherapy. The drug most often used is Temozolomide. Chemotherapy is prescribed and supervised by a Specialist Medical OncologistFor more information see the link below or contact your Medical Oncologist

Click here for more information

Oligodendrogliomas

Oligodendrogliomas arise from supporting cells called oligodendrocytes. They are generally slower growing and better controlled than astrocytomas. At present they are graded as

• Grade II - Oligodendroglioma
• Grade III - Anaplastic oligodendroglioma

Treatment for Oligodendroglioma is very similar to astrocytomas. A genetic discovery was made about 10 years ago about oligodendrogliomas. We now routinely test the tissue obtained for these genetic variations. It tells us which patients are likely to have a better prognosis and also may select tumours that respond well to chemotherapy.

Metastatic Tumours

Malignant tumours that arise elsewhere in the body may secondarily seed in the brain. Malignant tumours shed cells that can enter the blood stream. At any one time, a third of our total blood volume is in the brain. This makes the brain a common site for secondary brain tumours. There may be only one tumour in the brain or many. In Australia we have a very high incidence of melanoma and so there is a high incidence of metastatic melanoma to the brain. Other cancers that seed in the brain are breast, lung and colon. Melanoma in the brain has a tendency to bleed and cause a sudden rise in the pressure of the brain.

How do we treat secondary tumours in the brain?

Surgery

Surgery may be performed on up to 4 tumours in brain. Whether they can be safely removed or not depends on the location.

The surgical technique that Dr Shivalingam uses adheres to the principles of minimally invasive surgery and utilizes stereotactic navigation.

Radiotherapy

For deep lesions within the brain, surgery may be too risky. For these, these we use a form of focused and targeted radiotherapy called Stereotactic Radiosurgery (SRS). Once surgery or SRS has been performed, it is well established for most metastatic tumours that whole brain radiotherapy (WBRT) is needed to control further growth.