30% of all women with metastatic breast cancer will eventually develop brain tumors. 30% of these women will not experience symptoms until their tumors are too large to be treated through non-invasive procedures. Herceptin and other drugs may keep the primary cancer under control but do not cross the blood brain barrier. This results in HER2 positive patients having a higher incidence of brain tumors. We encourage all metastatic breast cancer patients to request brain MRI's to be performed on a regular basis. Be familiar with all of the symptoms and immediately tell your oncologist should you experience any of them.