sometimes dietary changes CAN help... but I am sure that Shannon has already heard about and tried many different options. As someone who is not a close friend and intimately aware of what she is doing and what she is going through, I wouldn't presume to tell her that X diet will work.... that being said, I am also sure that the person offering dietary advice meant well.
I am a cancer survivor and if you talk to other cancer survivors... many of us have tried, with success, different dietary changes. But the reality is that not everything works for everyone. Not even all allopathic treatments work for everyone.
I can't even imagine what Shannon is going through. I hope that she is able to get the treatment she needs and that her life gets better.