A Study of Local Therapy for the Treatment of Brain Metastases From HER2 Positive Breast Cancer

"Neurosurgery: The decision whether or not to recommend neurosurgery will be made independently of this research study. The complexity and length of the surgery depends on the size and location of the tumour(s).~Stereotactic Radiosurgery: If the participant will be receiving stereotactic radiosurgery (either alone or in combination with neurosurgery), the Radiation Oncologist will organise for the participant to have a Radiotherapy planning. Single metastasis, smaller than or equal to 2cm, may require 1 fraction. Alternately, multiple metastasis, metastasis in the brain stem, or those bigger than 2cm will required multiple fractions to treat. The dose range for the study is 20Gy/1 fraction to 24Gy/3 fractions."