What should you know about HER2-positive brain metastases?

The word metastases means cancer cells have spread to the brain from another part of the body. HER2 is a protein that can help some cancer cells grow; testing the original tumour and, when possible, a metastasis helps the team choose medicines that target this feature. Brain involvement can cause headache, nausea, seizures, weakness, balance changes, speech difficulty, confusion or altered vision, although symptoms vary.

The care team may use brain imaging, neurological assessment and information about the original cancer to decide whether treatment should focus on a small number of areas, wider brain involvement, symptoms, or disease elsewhere.

Treatment may combine a HER2-directed systemic medicine with local treatment. Stereotactic radiosurgery can focus radiation on selected deposits, while whole brain radiotherapy treats a broader area. Brain tumour surgery may be considered when removing a deposit could relieve pressure, provide tissue for testing, or improve control of a suitable lesion.

Keep a record of new symptoms, medicines and seizure activity. Do not stop cancer treatment or anti-seizure medicines without speaking with the oncology team. Ask how the proposed plan fits with treatment for the original cancer, such as breast cancer, lung cancer or melanoma.

Seek emergency help for a first seizure, a seizure that does not settle, sudden weakness or numbness, new trouble speaking, severe confusion, fainting, repeated vomiting, or a rapidly worsening headache. Contact the oncology team promptly for a new or steadily changing symptom, even if it seems mild, because neurological changes may need examination and imaging.

Ask which brain areas are involved, whether swelling is present, which HER2-directed options are suitable, and whether focused radiation, whole brain radiotherapy or surgery is recommended. Ask how treatment may affect memory, driving, work and daily activities, and which symptoms should trigger emergency care.