Over the past many years my diet has slowly evolved to, "If it comes from something that has eyes (or parents), don't eat it". For me, the major exceptions are fish and feta cheese. Since my beer has a head (but no eyes) I still drink it.
I've done this mainly for heart considerations; however, from what I read "vegen" is good for overall health and may be good for Cancer. There's a ton of books out there on the subject, a couple you might be interested in are Dr. Moyad's, "Promoting Wellness for Prostate Cancer Patients" and the "China Study", by T.C. Campbell. The later is a big time vegen push .... Campbell also has a web site and a movie covering vegen. Google him and you'll get a lot of information.
I started with Mike Milken's cookbooks (The Taste for Living Cookbook). Milken attributes his successful battle against G9 PCa to vegen.
I'm not sure if any of what I've read is real ... I do know I've lost weight and feel real good. I've also increased exercise, and added some vitamins (e.g. D3).