Dad been diagnosed with possible brain tumour, requesting advice from possible neurosurgeons/survivors?

Well its understandable, he has a brain tumor on the right side, and its affecting all of the functions of the left side of the body, its the tumor that is causing it, and its most likely growing at a rapid pace. The dexamethasone is for the inflammation it has a very strong potency compared to the normal prednisone about 30x. However, its also an immunosuppressant. Most likely, its suppressing the immune system which targets those cancer cells. Either way it could be beneficial, it could be detrimental. He would have to do a biopsy in order to determine the staging of the tumor, and to see if it is malignant. They might not be able to remove all of it depending on how vascularized it is. How old is your father, it could make the physician chose a less risky procedure, especially if he has any other health problems. They need to get some sample tissue to determine the staging as well as other characteristics of the tumor, and that will help with determining the treatment modalities.