You are posting with the patient community, not doctors - so it would probably help to post in the expert area (but he only answers once a week or so).
Glioblastoma is likely the name of the tumor. Since she had the biopsy - can you/she get a copy? If they changed her treatment plan after the biopsy, then something has to be in the report that needs to be known.
1. steroids have a lot of side effects. Yes, it can reduce swelling but they may have found that it was not doing anything so why subject her to the side effects?
2 - www.clinicaltrials(at)gov is where you can find clinical trials. You can search by location, by tumor etc. so you can search.
3. As I am a patient, I don't know about the vaccine. I did have an uncle with this type of tumor. You probably have to look for a trial but she probably has to be in good shape - in some early stage.
4. Read up on the clinical trials site.
5. Your doctor should also be advising your aunt - are you her medical advocate? On her hippa etc so you can get her medical info and talk to her docs?
http://www.medhelp.org/forums/Brain--Pituitary-and-Skull-Base-Tumor-Forum/show/994?camp=msc&personal_page_id=862364 is a good place to post and I see you already posted there.
Your aunt's condition should drive what should and should not be done - and consult her doctor if you have questions.