You might want to look into exogenous ketone supplementation - they can help and/or even force the body into ketosis overcoming diet.
Here's some good info for you in order of increasing depth .
Keto/Cancer
There are ketone salts & ketone esters and here is some good insight about them.
I couldn't find this on YT, but here is a link to
Dr. Peter Attia discussing it with Dom as well and as they say in the notes
"Dom also discusses the strategy and tactics of the metabolic management of cancer, which includes, but is certainly not limited to, a ketogenic diet (KD). Cancer is covered throughout this episode, but if there’s one section to listen to, skip ahead to the 2-hour mark and listen to what Dom has to say about the Press-Pulse approach."