Cancer in any area of the body may spread to the brain, and this is known as a metastatic brain tumour.Common primary sources of metastatic tumours include the breast, lung,skin, kidneys and bowel. Metastatic tumours generally contain the same type of cells as the primary tumour, so it’s possible to determine the source by examining the tumour’s tissue. Metastatic brain tumours can develop as a single tumour, but more often arise as multiple tumours.
Occasionally the primary source of cancer is not known at the time of discovery of a secondary tumour. Metastatic brain tumours are more common than primary brain tumours and occur in approximately one fourth of all cancers that spread through the body.
Symptoms develop over time, and onset may not occur until the later stages of the disease. Symptoms are caused by the pressure the tumour exerts on brain tissues, swelling from the leakage of fluid around the tumour or bleeding from ruptured blood vessels within the tumour.
Symptoms will vary depending on how large the tumour is and it’s location in the brain. They also tend to worsen as the cancer progresses and the tumour grows larger. Some patients will have no symptoms and accidentally find out they have a metastatic tumour through MRI imaging. Depending on the location, number and size of the metastatic tumour(s), symptoms can include:
- Headache – one of the most common symptoms caused by swelling.
- Seizures – caused by pressure and swelling
- Weakness, balance and coordination problems
- Numbness in the limbs or face
- Visual disturbances
- Alterations in behaviour, mood and/or personality
A CT or MRI imaging is needed to diagnose a metastatic brain tumour. Most cancer patients have routine scans over the course of their treatment to detect metastases. Patients with metastases who begin to show signs of neurological symptoms will be given a scan of their brain. In rare cases, a biopsy may also be recommended to determine an exact diagnosis. If the brain metastasis is discovered first, additional tests will be required to locate the source of the primary tumour.
There are several different treatment methods for metastatic brain tumours and these will be tailored to each patient’s condition. The size and location of the tumour, as well as the age and overall health of the patient will determine treatment. A patient’s oncologist, radiation oncologist and neurosurgeon will work together to determine which approach is best. Treatment may include a combination of surgery, radiation and chemotherapy.
The aim of surgery is to completely remove or reduce the size of the tumour to ease symptoms caused by pressure, or to make radiation therapy possible. If the primary source of the tumour is unknown, surgery may be performed to gain a diagnosis through tissue pathology. After surgery and treatment, doctors will review the results and decide on a further course of action.