What causes brain metastases?

A metastasis is a secondary tumour, so it begins with cancer elsewhere in the body rather than starting as a primary brain tumour. Cancer cells can enter blood vessels, circulate, and settle in brain tissue. The new tumour can cause symptoms by affecting nearby brain areas or by increasing pressure inside the skull.

Lung cancer, breast cancer, and melanoma are among the cancers that can spread to the brain. Having one of these cancers does not mean brain metastases will occur. Symptoms can vary with the location and size of a tumour and may include headache, seizures, weakness, speech changes, confusion, or vision problems.

Tell your oncology team promptly about a new or changing headache, balance problem, weakness, numbness, speech difficulty, memory change, or seizure. They may review your cancer history, perform a neurological examination, and arrange brain imaging. Treatment choices depend on the number, location, size, and behaviour of lesions and on the primary cancer.

Keep a record of when symptoms start, how long they last, and whether they affect walking, speaking, sight, or alertness. Take prescribed medicines as directed and do not drive if you have had a seizure or your alertness is impaired.

Call emergency services for a first seizure, a seizure lasting longer than usual, sudden weakness on one side, new trouble speaking, loss of consciousness, severe worsening headache with vomiting, or rapidly increasing confusion. These signs can reflect a neurological emergency and should not wait for a routine appointment.

Ask whether your symptoms need urgent imaging, what other causes should be considered, and how the primary cancer affects treatment choices. You can also ask about seizure safety, driving, steroid treatment, and which changes should prompt an emergency call.