What about sugar, glucose/sucrose/fructose or similar products??? They are supposed to give energy to the cancer cells. Although they are many kind of unrefined sugar (agave, Palm sugar, honey) but the molecules are glucose based. In the lab test cancer cells get their energy from glucose. If you go for CT/PET scan you would be asked to fast, this is because during the fasting our body cannot produce glucose to fuel the cancer cells which makes them inactive, but the hospital will inject glucose intravenously half an hour before scanning, this is to activate and fuel the cancer cells so it can be detected by the machine.
In my opinions just being vegan and vegetarian are not enough, one needs to do more. sugar free! Sugar substitutes like xylitol, stevia or erythritol are considered safe and is not glucose based. But it is not easy to find deserts or sweets that are sugar free. Then there are the questions about the use of toxic pesticide, fungicide and herbicide in our fruits & vegetables farming practice. Many sprays used are carcinogens. Hence to eliminate that, organic vegetables are consider safe but expensive. So many other factors that could influence whether we would get cancer or recurrence despite being a vegetarian or vegan. To name a few: daily makeup and toiletries use that contain carcinogenic ingredients such as paraben, aluminium sulphate, Stress level, Pollution, exposure to toxic items in foods , household items and toiletries, etc. There is no straight answers. But your life style influence the outcome.
strengthen your immune system, take supplements that helps prevent cancer.
One particular book that has compiled a lot of data of cancer survivors that tracked people all over the world on what they do to have long term remission is called "Radical Remission" by Kelly A Turner PhD. Buy it from Amazon. It is an eye opening. But most of her data shows that those who able to keep the cancer at bay are embracing vegetarianism or being vegan, plus other life style changes.
