What Is The Life Expectancy Of A Person With Astro Sarcoma Brain Tumour?

I have a very close friend who was just diagnosed with an astrosarcoma of the brain. She tells me that this is a very aggressive tumor with one of the worst prognoses. The tumor was already quite large, and has been respected. She now faces a month of both chemo and radiation which I expect will be quite debilitating. I am a Physician Assistant, with 30 years of clinical practice, but know very little about this tumor type. What is the average life expectancy with the above treatment plan? I have promised her that I would help when things get bad so she can remain at home for as long as possible. I live in upstate NY and she lives in Washington DC. I still work full time, but only 3days a week. I know that each patients course can be quite variable, but just wanted a little more general information about her condition. Sincerely, Jean Loughrey.