Oh no, very sorry to hear that
I read a book called 'The Anti-Cancer Diet' recently, during a bout of paranoia about cancer:
http://www.amazon.com/Anticancer-New-Li ... 0670020346
I found it really helpful - the author is a doctor who survived a brain tumour. His main area of focus is on eating foods which cause inflammation (as cancer cells apparently need to inflame surrounding tissue to establish their blood supply) and on ceasing to eat dairy products (as apparently they contain growth hormones which inadvertently cause cancer cells to divide faster). He also swears by organic.
I am not in a position to know whether or not his advice is medically sound, but it made sense to me and there is also a chapter on the mental side of dealing with cancer.
I hope all goes well for your friend. I went to a wedding in August for a couple in their early thirties - the groom has since been diagnosed with terminal kidney cancer. It is a truly revolting disease.