Earlier quoted context omitted.
No medical experience, other than as a patient... however I read the body can live up to two months without food (but with adequate water). If you managed to survive longer than the cancer cells, wouldn't they just come back after defeat? Doesn't this stem from DNA?
Dumb question: why two months? Doesn't it depend on your fat reserves? If you are 350 pounds, can't you just not eat until you are 150 and be fine? (I am not suggesting that this is true or that anyone should try it; I don't know and I am asking the question.)
However, metabolism has non-energy needs which are supplied through food: vitamins, minerals, protein, and some fats that cannot be synthesized iirc. Though these needs are greatly reduced when fasting, they do not go to zero.
Google “angus barbieri” for the most famous, though not unique, example for medically documented long term fasting.