Lowering cellular energy is the tactic used by most chemo drugs, and chemo has a horrible success rate. It is also a method that works best with cancers in early stages. See:
I highly suggest looking at oleander extract as well as large amounts of N-Acetyl Cysteine and turmeric/curcumin. See:
http://www.tbyil.com/Oleander_Cancer_Discussion.htm
http://www.tbyil.com/Apoptosis_versus_Defense_Mechanism.htm
Oleander has had notable success against childhood brain cancers. N-Acetyl cysteine is considered to be an essential complimentary supplement and it provides essential glutathione.
Turmeric and its main constituent content curcumin have gained huge notice in recent years for their ability to fight cancers, including brain cancers. A big plus is that curcumin is also a good natural anti-inflammatory and inflammation is always a big concern with brain cancers due to the brain/tumor swelling in a confined space (the skull).
Google "curcumin brain cancer" and you will find many helpful links.
Another item which has had remarkable success against brain cancers in children (and adults as well) is cannabis oil - which might be difficult to obtain depending upon what state you live in. If it were me, I would find a way to get some no matter what it took.
Google "cannabis oil brain cancer" to see what I am talking about.
In my opinion, beating cancer should be an all-out comprehensive program which includes getting rid of and avoiding toxins, healthy diet and nutrition, cancer fighting and immune boosting foods and supplements, stress management, daily sunshine/Vitamin D3 and more.
You can find many articles about cancer written by myself and others at my site's article directory:
http://www.tbyil.com/articles.htm
Another site which has a tremendous amount of information is cancertutor.com And the cancer alternatives forum here has many, many posts with good information too.
I hope that helps and wish the young girl the very best.