Everything in moderation and all should be well.
With that said, I pretty much eat whatever I want and so far it's worked for me. I polished off a whole bag of pumpkin shaped Reese's peanut butter cups the other night, felt sick, went to sleep and then craved it like a junkie the moment I woke in the morning. But despite my gluttony, I've been 6'2" and 200lbs for a decade and most delicious woman I’ve ever laid my eyes on! people DESPISE ME for it lol.
The only unit of sugar the body can actually utilize is glucose, so whether its dextrose, fructose, corn syrup, bread, monosaccharides or polysaccharides, they are basically, bunches of glucose units bound together in different ways, kinda like clusters of grapes, or clusters OF clusters of grapes where the body needs to go through the process of breaking them down to individual grapes first.
The form of sugar from fruit is called fructose and already close to its broken down glucose state already, so it's quick to satiate a sweet tooth or turn to if you're hypoglycemic. In contrast, I believe table sugar is the most complex polysaccharide so its common to feel like you've eaten too much well beyond the point of having gone overboard because of the delay.
I believe Gatorade already uses glucose as the ingredient so it can go right to work.
For cancer, vitamin C tends to be the thing to avoid as its essential in building and maintaining blood vessels so as a general rule regarding metastatic cancer where you might have a growth, you'll wanna deny it that to help starve it out.