Brain metastases !

Cancer that has spread to the brain from another organ, most often the lung, breast or skin. It is the most common brain tumour in adults.

Updated 2026-11-01

Structures involved

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Why it happens

What it is

Secondary tumours in the brain from a cancer that started elsewhere, usually spread through the blood. They are the most common intracranial tumours in adults and are often multiple, located at the junction of grey and white matter.

Who gets it

Up to a fifth to a third of adults with cancer develop brain metastases. The most frequent primary sites are lung, breast, melanoma, kidney and colorectal cancer. In Colombia, where lung and breast cancer are among the main causes of cancer death, brain metastases are a frequent reason for neuro-oncology and palliative care consultations.

Causes

Lung cancer (the most common source, especially small cell and adenocarcinoma)
Breast cancer (especially HER2-positive and triple-negative)
Melanoma (the highest tendency to spread to the brain; often hemorrhagic)
Renal cell carcinoma (often hemorrhagic)
Colorectal cancer (more often in the posterior fossa)

Risk factors

Advanced or poorly controlled systemic cancer
Primary tumours with high brain tropism (lung, melanoma, HER2-positive breast)
Longer survival with modern cancer treatments, which allows more time for brain spread

Pathophysiology

Tumour cells reach the brain through the arterial blood and lodge where vessels narrow at the grey-white matter junction, mainly in the territory of the middle cerebral artery and at watershed areas. About 80% are in the cerebral hemispheres, 15% in the cerebellum and a few in the brainstem. The tumour and the vasogenic edema around it raise intracranial pressure, irritate the cortex (seizures) and compress neighbouring tissue; posterior fossa lesions can block the fourth ventricle and cause hydrocephalus.

Classification

By number: single (one brain lesion), solitary (single and the only metastasis in the body) or multiple
By location: supratentorial, infratentorial (cerebellum, brainstem), or leptomeningeal spread

Symptoms and signs

Headache, often worse in the morning or with coughing and straining
Nausea and vomiting
Focal weakness, numbness, language or visual problems depending on location
Seizures
Changes in cognition, personality or behaviour
Imbalance and gait ataxia with cerebellar lesions

Diagnosis

Clinical: Suspected in any patient with cancer and new neurological symptoms; in some patients the brain lesion is the first sign of the cancer. Performance status helps decide treatment.
Tests: Search for the primary tumour and staging; biopsy or resection gives the diagnosis when the primary is unknown or there is doubt. Molecular testing of the tumour (e.g. EGFR, ALK, HER2, BRAF) guides targeted therapy.
Imaging: Contrast-enhanced MRI is the test of choice: ring-enhancing or solid lesions at the grey-white junction with disproportionate surrounding edema. CT with contrast is used when MRI is not available; chest, abdomen and pelvis CT or PET-CT looks for the primary.

Differential diagnosis

Primary brain tumours (glioblastoma, lymphoma, meningioma)
Brain abscess
Toxoplasmosis in people with HIV
Neurocysticercosis (frequent in Colombia and Latin America)
Tuberculoma
Ischemic or hemorrhagic stroke and demyelinating disease

Goal of treatment

Control symptoms and edema, achieve local control of the brain lesions while protecting cognition, and treat the systemic cancer, in line with the patient's prognosis and wishes.

Treatment

Medical: Corticosteroids (dexamethasone) to reduce vasogenic edema in symptomatic patients; antiseizure drugs only after a seizure, not for prevention.
Surgical: Surgical resection for a single accessible lesion, large lesions with mass effect, or when tissue diagnosis is needed, usually followed by radiotherapy to the cavity.
Procedure: Stereotactic radiosurgery for a limited number of small lesions; whole-brain radiotherapy (with hippocampal sparing when possible) for many lesions.
Medical: Systemic therapy that crosses into the brain, such as targeted therapy for EGFR, ALK or HER2 tumours and immunotherapy for melanoma and lung cancer.
Follow-up: Neurological checks, seizure precautions, glucose monitoring while on corticosteroids, and early palliative care for symptom control and decision-making.

Complications

Brain herniation from edema
Hemorrhage into the tumour
Obstructive hydrocephalus
Seizures
Cognitive decline after whole-brain radiotherapy, and radiation necrosis
Side effects of corticosteroids (hyperglycemia, infections, myopathy)

Prognosis

Prognosis depends on age, performance status, number of lesions, control of the systemic cancer and molecular markers. Median survival ranges from a few months to several years in patients with targetable tumours.

Test yourself

Think of the answer, then tap the question to see it.

What is the most common intracranial tumour in adults?

Brain metastases.

Which primary cancers most often spread to the brain?

Lung, breast, melanoma, kidney and colorectal cancer; lung cancer is the most common source.

Where in the brain do metastases typically lodge?

At the grey-white matter junction, often in the territory of the middle cerebral artery.

Which metastases are classically hemorrhagic?

Melanoma, renal cell carcinoma, choriocarcinoma and thyroid cancer.

Which drug is used to reduce edema around brain metastases?

A corticosteroid, usually dexamethasone.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: Metastatic brain tumor: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2026).

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Representative model, for educational purposes only.

White matter highlighted on the Durgical 3D model