Gina Kolata. Nuf said about that.

For cancer, we could look at the work of Feinman for example, where patients with cancer saw regression of tumors when they ate a ketogenic diet. This is a human experiment. It trumps mice and petri dish experiments.

https://feinmantheother.com/

Follow the link above, check the posts "Ketogenic Diets for Cancer". Link to discussion on the experiment (with link to Feinman's blog post about it in the first post) : http://forum.lowcarber.org/showthread.php?t=447278

Bear in mind this is a therapeutic experiment, not a preventive experiment. But it's easy to extrapolate and conclude that the same diet used as therapy here can be expected to prevent as well. Rather, it's absurd to conclude that the same diet used as therapy was also used to cause the disease, see?