Welcome to the forum Bowen although I'm sorry to hear that your sister has been diagnosed with a malignant brain tumour.

Waiting for more information about a cancer diagnosis can be very tough but I just wanted to let you know that you're not alone. Many members here will really understand what you are going through at the moment having been in similar situations with their siblings and parents and I'm sure some of them will post soon to offer their support and advice. In the meantime try not to let your mind run away from you if you can and stay busy until you find out more about the diagnosis from your sister. 

Do let us know what happens if you can, we'll be thinking of you and hoping for the best outcome possible in this situation.

Kind Regards, 

Steph, Cancer Chat Moderator