Cancer starts in one part of the body such as the breast, lung, etc and can spread to other areas such as liver, brain or bones etc. The place of origin is called as the primary site and the areas it has spread to are called as secondary sites and cancer there is known as secondary cancer or metastatic cancer.
Brain metastases are when cancer spreads into the brain. Common cancers that spread to the brain are breast, lung, kidney and cancers of the gastrointestinal tract.
There are mainly two types of brain metastases. One of them is a solid metastases, where the cancer in the brain is solid in nature. The other is a cystic metastases, where the metastases is like a fluid filled sac. There can be mixed with solid and cystic components.
Brain metastases can cause symptoms depending on the area in the brain that is affected by the metastases. Common symptoms that patients present with include
Headaches
These are common and are more persistent than usual headaches, can be more in the morning on waking up and can be dull aching or throbbing in nature. Headaches may be associated with vomiting or a feeling like vomiting(nausea).
Gait disturbance
People with brain metastases may have symptoms of unsteadiness on their feet or being unable to walk. They can have vertigo, loss of balance or a tremor.
Nausea and Vomiting
A feeling of vomiting or actual vomiting associated with other symptoms can happen in a person with brain metastases. Vomiting can be regular and more forceful.
Weakness
A weakness in arms or legs or one half of the body can be a symptom of brain metastases.
Fits
Fits or seizures can be a symptom of brain metastases. These fits can be partial involving one part of the body or total involving the whole body and associated with drowsiness.
Memory, Mood, Confusion
A recent loss of memory, confusion or new onset of low mood or change in personality can all be symptoms related to brain metastases.
Eye disturbances
Visual disturbances are seen in patients with brain metastases. They can be blurring of vision, double vision or absent of vision when looking to one side
When brain metastases are suspected, the following tests can be done.
CT Scan of the brain
A contrast enhanced CT scan of the brain is done to look for brain metastases. The scan is quick but generally less sensitive than an MRI to pickup up smaller brain metastases.
MRI Scan
A contrast enhanced MRI scan of the brain is the best test to look for brain metastases when there is a suspicion. MRI scan provides better detail than a CT scan or other scans.
Biopsy
A biopsy of the suspected area in the brain is not commonly done to make a diagnosis of brain metastases. It is done more in patients who do not have a recent history of cancer or the findings on the scan are not suggestive of brain metastases.
Whole body CT or PET-CT scan
Sometimes, brain metastases are diagnosed first before the cancer that may have started elsewhere. CT or PET-CT scans are done in that circumstance to find the original site where the cancer started and spread into the brain.
Treatment options for brain metastases is dependent on the fitness of the patient, the behaviour of the cancer in the rest of the body and response to previous treatments and the number of metastases seen in the brain. Treatment is individualised based on all these factors.
Steroids
Steroids are drugs that are used to treat brain metastases. When cancer spreads into the brain there is accumulation of fluid (cerebral oedema) around it. This leads to increase in pressure in the brain causing worsening of all symptoms. Steroids help reduce the fluid in the brain, thereby improving symptoms. Dexamethasone is the steroid that is most used in this setting. It is taken in the form of tablets or injections. When taken as tablets, it should be taken after food to prevent irritation of the stomach. Other tablets are given along with it to reduce this irritation. When taken for a prolonged period, steroids cause side effects of weight gain, swelling of face, reduced immunity among other things.
Anticonvulsants
These are drugs that are used to reduce the risk of fits in patients who already have had fits or are at high risk of having fits. Many drugs are available that can be used for this purpose.
Surgery
Surgery and removal of brain metastases is an option of treatment. It is used more often in patients with limited number of metastases (mainly single metastasis) in the brain, cancer well controlled in other parts of the body and good fitness of the patient. The metastases should also be present in a part of the brain where surgery is possible. Surgery may sometimes be able to remove only a part of the tumour. Radiotherapy is used after completion of surgery to reduce the risk of the cancer coming back in the brain.
Radiotherapy
Radiotherapy is an option of treatment of brain metastases. In most patients with brain metastases, radiotherapy is used as the only treatment along with steroids to treat this condition. Different radiotherapy techniques are available to this condition.
For a single or very limited number of metastases that are small, stereotactic radiosurgery (SRS) is an option of treatment. SRS involves giving a high dose of radiation to the abnormal area in the brain in an ultraprecise manner using modern radiotherapy machines. Treatment can last from 5-40 minutes depending on the machine used. If SRS is not possible, fractionated stereotactic radiotherapy (FSRT) is used as this will be able to treat slightly larger metastases than SRS.
For patients who are not very fit or have more brain metastases and in whom the above mentioned techniques are not suitable, whole brain radiotherapy is used. Here treatment is given to the whole brain over 5-15 days. In some patients, a mixture of whole brain and SRS or FSRT can also be used. Side effects of radiotherapy include tiredness, hair loss, sleepiness, headaches, nausea and vomiting, small long-term risk of reduced memory and concentration. Radionecrosis is a long-term side effect of SRS and FSRT treatment.
Chemotherapy
Chemotherapy is not a common treatment option for brain metastases as most chemotherapy drugs do not go into the brain due to the presence of a blood brain barrier. It is only used in some settings.
Biological therapy
Biological or targeted therapy include drugs that target specific areas of the cancer cell. In view of the blood brain barrier, only some drugs are effective in controlling brain metastases and can be used in treating breast and lung cancers.
