Just to add to the discussion, I've been vegetarian since the 1990s, when I had some kind of stomach flu and developed an aversion to meat afterwards.

As decades of research suggests, the absence of red meat, especially, from my diet has led to excellent *colon* health (I haven't had even the tiniest benign polyp show up yet in a colonoscopy, unlike my siblings), but it didn't stop me from developing advanced prostate cancer.

Healthy eating is good for many reasons, but there's no magic preventative for all cancers.