What are brain Metastases?

Metastases (short for 'metastatic tumors') are those which do not arise from within the brain tissue itself, but are spread there from a tumor outside the nervous system. They are the most common type of 'brain tumor'. Whereas tumors arising from nervous system itself often occur alone, metastases often occur as multiple tumors in more than one place in the nervous system. Even for patients having a single nervous system tumor however, almost one half are eventually shown to be metastatic.

Where do they come from?

Brain metastases are most often due to the spread of lung and breast cancers. Some more rare types of cancer seem also to have a predilection for spreading to the brain and include kidney cancer (renal cell carcinoma), certain skin cancers (melanoma) and testicular cancer. On the other hand, some types of cancer (e.g. prostate cancer) almost never spread to the brain. For patients suffering systemic or wide spread cancer, one quarter to one third will develop brain metastases during the course of their disease.

What are the symptoms of Metastases?

Because metastatic tumors are slowly growing masses, they usually cause gradual onset of symptoms related to the area of the brain they are compressing or invading. This can include weakness or numbness of parts of the body, headache, cognitive dysfunction, speech difficulties and seizures.

How are they diagnosed?

Patients suspected of having metastatic brain tumors usually undergo either CT scanning or MRI scanning of the brain. These scans are usually done following intravenous injection of a dye that increases the sensitivity of the scan for picking up tumors. Of the two tests, the MRI is more sensitive.

How are they treated?

The aims of treatment are to cure the tumor if possible, and to preserve function and quality of life. Treatment can be surgical or non-surgical or both. The choice of treatment depends on the type of cancer, whether the patient is medically stable and the patients life expectancy and expected quality of life both during and after treatment. Often brain metastases are treated first with a steroid (dexamethasone) to reduce swelling around the tumor(s) and an anticonvulsant (e.g. phenytoin) to prevent seizures from occurring.

Patients with tumors of unknown source will require investigation to determine where the original (primary) tumor is. This might include blood tests, chest Xray, mamography, ultrasound or CT scanning of the abdomen and pelvis, and radionucleotide bone scanning.

In the case that a 'primary' tumor is found outside the brain, a biopsy is usually taken to determine the exact type and to aid in planning further treatment. If no source is found and the brain tumor is solitary, surgery to remove it may be done depending on it's size and position. Alternatively, the brain tumor may be biopsied. Either of these surgeries might be followed by non surgical treatments of radiation and / or drug therapy (chemotherapy) depending upon the type of tumor involved.

If the tumor is widespread either inside or outside the nervous system, usually only non surgical treatment therapies are done.

What can I do?

If you have a cancer that is know to sometimes spread to the brain be on the lookout for symptoms of spread.

If you have been diagnosed with brain metastases discuss your options carefully with your doctor. Know what to expect. Discuss your treatment wishes early in your course with your family and your doctor so that they can carry them out for you in case you are later incapacitated.

Therapy can be arduous even when curative. Get some support from your family or friends  or join a support group. Watch out for depression and let your doctor know if you are having trouble.