Brain Metastases — Understanding When Cancer Spreads to the Brain

Many symptoms are driven by the swelling (oedema) around a lesion rather than the lesion itself. Corticosteroids reduce this swelling and can ease headache, weakness and confusion within days — often before any radiation or surgery. If you have had a seizure, anti-seizure medication is started and managed by the team. These supportive steps are usually the first thing we put in place, because feeling better quickly matters, and because a calmer, clearer patient can take part in the bigger treatment decisions that follow.

Stereotactic radiosurgery delivers a high, focused dose of radiation to each metastasis from many angles at once, without any incision — despite the word "surgery", no cutting is involved. It is delivered as part of coordinated specialist radiation care and is often preferred over whole-brain radiation when the number of lesions is limited, because it spares much of the healthy brain and better preserves memory and thinking. Treatment is usually completed in 1 to 5 outpatient sessions. Modern guidelines support treating several metastases this way rather than defaulting to whole-brain radiation.

Whole-brain radiation treats the entire brain and is used in selected situations — for example when there are many lesions, or when tiny deposits are likely beyond what a scan shows. It can be very effective at controlling disease, but because it treats healthy brain too, it can affect memory and thinking, so it is weighed carefully against focused radiosurgery. If whole-brain radiation has been recommended to you, it is reasonable to ask whether radiosurgery is an option first — a common reason patients seek a second opinion. Techniques that protect the memory centres (hippocampal-sparing) may also be discussed.

Because brain metastases are secondary tumours, systemic (whole-body) therapy is chosen to match the primary cancer. Depending on the cancer type and its molecular features, this may be targeted therapy, immunotherapy, or chemotherapy (described here by class rather than brand). Importantly, some modern targeted and immune treatments cross into the brain and can shrink brain lesions too — which has changed how metastases from cancers such as lung, breast and melanoma are managed. CION's medical oncology team delivers systemic therapy directly and coordinates it with your radiation plan through the tumour board.

Surgery is considered mainly for a large single metastasis causing significant pressure, or when tissue is needed to confirm the diagnosis. Removing such a lesion can relieve symptoms quickly and is often followed by focused radiation to the surgical bed. CION does not perform neurosurgery in-house; all neurosurgical steps — resection, stereotactic biopsy, neuronavigation — are coordinated with accredited neurosurgical partners, while CION delivers the imaging, radiation planning, systemic therapy and supportive care directly. The tumour board decides together whether surgery, radiosurgery or systemic therapy leads for your situation.

Alongside cancer-directed treatment, supportive care protects how you feel and function day to day. This can include physiotherapy for weakness, speech therapy, help with memory and fatigue, pain and nausea control, and emotional and family support. Because a brain-metastasis diagnosis affects the whole family, we make time to explain what is happening and what to expect. Our approach is to make decisions for healing, not billing — with transparent costs discussed up front, so you can focus on getting the care you need.

Brain metastases are secondary brain tumours — cancer that has spread to the brain from a primary tumour somewhere else in the body, such as the lung, breast, skin (melanoma), kidney or colon. They are different from primary brain tumours, which begin in the brain itself. In fact, brain metastases are the most common type of brain tumour in adults, more frequent than primary tumours. Because they are secondary, treatment always considers both the brain lesions and the original cancer. Learn which cancers most often spread in our guide on cancers that spread to the brain.

A primary brain tumour starts in the brain or its coverings — for example a glioma or meningioma. Brain metastases (secondary brain tumours) start elsewhere in the body and travel to the brain through the bloodstream. Under the microscope, brain metastases look like the original cancer — lung-cancer cells in the brain are still lung-cancer cells. This matters for treatment: the systemic (whole-body) therapy is chosen to match the primary cancer, while focused radiation or surgery targets the brain lesions. Metastases are also more likely to appear as several separate lesions.

Symptoms depend on where the lesions sit and how much swelling surrounds them. Common signs include a new, persistent or progressive headache (often worse in the morning), seizures, weakness or numbness on one side, trouble with speech or vision, unsteady balance, and changes in memory or personality that family notice first. Many people have more than one symptom. For a full guide, see our page on brain metastases symptoms. If you have a known cancer and develop any new neurological symptom, ask your oncologist about a brain MRI.

The key test is a contrast-enhanced MRI of the brain — the most sensitive way to detect and map metastases, showing their number, size, location and the swelling around them. A CT scan is used first in emergencies to rule out bleeding. If the primary cancer is unknown, the team searches for it, and occasionally a small biopsy of the brain lesion is needed to confirm the type. Any neurosurgical step is coordinated with accredited neurosurgical partners; CION delivers the imaging, molecular testing, radiation planning and systemic therapy directly, and reviews every case at a tumour board.

Treatment has two aims — relieve symptoms and control the lesions. Steroids reduce swelling and can ease headache and weakness within days, and anti-seizure medicine controls seizures. Stereotactic radiosurgery delivers precise, high-dose radiation to each lesion (as part of coordinated specialist radiation care) and is often preferred when lesions are limited, because it spares more healthy brain than whole-brain radiation. Systemic therapy — targeted therapy, immunotherapy or chemotherapy chosen for the primary cancer — can shrink brain lesions too. Surgery, coordinated with neurosurgical partners, is used for large single lesions.

There is no single survival number for brain metastases — outlook varies enormously and depends mainly on the type and extent of the underlying cancer, how many lesions there are, your general fitness, and how well the primary cancer responds to treatment. Modern targeted therapies and immunotherapy have improved outcomes for several cancers, and focused radiosurgery controls many lesions well. Both NCCN and EANO stress an individualised plan rather than a fixed prognosis. Your team will discuss what the numbers mean for your situation, sensitively and honestly — never as a guarantee.

For most patients brain metastases are treated to control the disease and protect quality of life rather than to cure it, because they signal advanced cancer. That said, outcomes have improved: a single lesion in an otherwise well-controlled cancer can sometimes be treated very effectively with surgery or radiosurgery, and some metastases shrink or disappear with modern systemic therapy. We avoid words like "cure" or "guarantee" — instead we explain realistic goals for your specific cancer. Book a free 45-minute consultation to review your MRI and reports — start here.