I don't have experience with this condition in dogs. I hope your little girl will be okay. Steroids are good for limited use and can be helpful, but I don't know about keeping her on them for too long. Ask your vet.
Is the tumor operable? And what would be the prognosis if it were removed? If it is benign, or hasn't metastased that might be an idea? If of course, she is fit enough generally for surgery.
I wish her well.