It's absolutely NOT a sure thing that cancer cells need glucose to live. But they do thrive on it. A PET scan literally puts a radioactive element in glucose, injected into your bloodstream after at least 6 hours of fasting, because the cancer will grab the sucrose and metabolize it first.
I keep the processed sugars to a minimum. I don't drink soft drinks often, I drink black coffee and unsweet tea. Most often if I have chocolate, it is dark semi-sweet.
There's a theory that you can investigate in a book the late Tommy Johnson Sr. wrote about his cancer battle. He was given 120 days to live, with a fast growing colon cancer. They stopped all treatment. He lived another 20+ years, and died of "old age/natural causes". It's basically diet and supplements. You can get his book on the Kindle, or the app for it, it is out of publication. I knew him, and I know his son.
I didn't have much trouble with chemo, I was fortunate, the chemo and radiation killed off my original tumor quickly, so I didn't get a massive long term dose, but Cisplatin is nasty. Of course, now I could not have regular radiation in the same area again. Cisplatin is so nasty, I had two nurses administer it, they both wore double gowns and double gloves. They had to repeat my name, date of birth, and dosage, to each other, and to the girls at the desk in the treatment room, quite loud. After it was finished, they flooded me with fluids, then gave me a shot of a drug so powerful that by the time the injection went through the IV, it felt like a tri axle dump truck was on my bladder. And I had to drink at least a full gallon of water that day and the day after. They told my wife not to touch anything if I got sick. It was about three months after treatment ended before they decided it was okay for us to have sex again.