Understanding brain metastasis: a guide for patients
Brain metastasis is a serious condition that occurs when cancer spreads from another part of the body to the brain. It is more common than primary brain tumours and can affect a person’s quality of life and neurological function. While the diagnosis can be frightening, a range of treatment options is available to manage symptoms and, in some cases, improve outcomes. In this article, consultant neurosurgeon Mr Ciaran Hill explains brain metastasis, how it develops, and how it can be managed.
What is brain metastasis?
A brain metastasis, also known as a secondary brain tumour, arises when cancer cells travel to the brain from another part of the body. These cells spread through the bloodstream or, less commonly, through cerebrospinal fluid. Once in the brain, the cancer cells begin to grow and form one or more tumours.
Unlike primary brain tumours, which originate within the brain, brain metastases are always linked to an existing cancer elsewhere in the body. They are typically a later-stage complication of a known malignancy, but in some cases, the brain metastasis is discovered before the original cancer is diagnosed.
What types of cancers can metastasise to the brain?
Several cancers have the potential to spread to the brain, though some are more likely to do so than others. The most common include:
- Lung cancer (the most frequent cause of brain metastases)
- Breast cancer
- Melanoma (a type of skin cancer with a strong tendency to spread to the brain)
- Kidney cancer
- Bowel cancer
In some patients, particularly those with melanoma or lung cancer, brain metastases may develop even when the primary tumour appears to be under control. The risk of brain involvement increases with more advanced stages of disease.
What are the symptoms of brain metastasis?
The symptoms of brain metastasis depend on the size, number, and location of the tumours. Because the brain controls a wide range of functions, symptoms can be diverse and may develop gradually or quite suddenly. Common symptoms include:
- Headaches, particularly new or worsening headaches
- Seizures, even in patients with no prior history
- Weakness or numbness on one side of the body
- Speech difficulties
- Problems with balance or coordination
- Changes in behaviour, memory, or personality
- Visual disturbances
Some patients may experience confusion or drowsiness, especially if the tumours are causing increased pressure inside the skull.
How is brain metastasis diagnosed?
If a patient with a history of cancer develops neurological symptoms, a brain metastasis is often suspected. Diagnosis typically involves imaging studies, with MRIs being the most sensitive and widely used tool. MRI can reveal the number, size, and location of metastatic tumours and whether there is associated swelling or bleeding.
In some cases, a CT scan may be used, especially in emergency settings. If the brain lesion is the first sign of cancer, further tests will be required to identify the primary tumour, including body scans, blood tests, and possibly a biopsy.
How is brain metastasis treated?
Treatment depends on several factors, including the number of metastases, their location, the type of primary cancer, and the patient’s overall health. Common treatment options include:
- Steroids such as dexamethasone, to reduce swelling and relieve symptoms
- Surgery in cases where there is a single accessible tumour, as surgical removal can provide symptom relief and improve survival in selected patients
- Radiotherapy which may include whole-brain radiotherapy or stereotactic radiosurgery (SRS), a highly targeted form of treatment ideal for small tumours
- Systemic therapy including chemotherapy, targeted therapy, or immunotherapy, depending on the cancer type. Some newer drugs can cross the blood–brain barrier and treat brain metastases directly
The choice of treatment is usually made by a multidisciplinary team, involving oncologists, neurosurgeons, and radiotherapists. In some cases, the goal is to control symptoms and maintain quality of life, rather than to cure the disease.