Has anyone heard about the Keto diet helping to fight tumours?

Thanks @Afraser and @kmakm for your logic.  I've developed major post treatment food anxiety, which I am sure a lot of people do after any serious illness. I'm obsessive/ neurotic about what my partner and I eat and end up in tears if I think I've eaten something 'bad' for me. I'm completely aware of how irrational my thinking is at the moment... just need to work on it!