Carbs raise insulin. Insulin promotes IGF1(insulin growth factor). Insulin growth factor promotes growth(that's why body builders use it) including cancers. How did someone like Lance Armstrong who was "healthy" get testicular cancer? It wasn't the testicular cancer fairy. No doubt his carbohydrate intake was HUGE . His intense exposure to endogenous IGF likely contributed.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6771568/
Note one piece of bread is not going to give you cancer. But eating processed carb/sugar loaded meals with snacks in between for decades is like pushing the IGF1 button all the time. Some of that is going to result in unwanted/unintended/unchecked growth.
https://en.wikipedia.org/wiki/Warburg_effect_(oncology)
If you are interested, please acquaint yourself with the Warburg Effect. Otto Warburg was a nobel prize winner in biochemistry 100 years ago. He identified that cancer cells produce lactate in huge amounts. This meant that cancer cells burned only glucose. Not fat or ketones. If you keep fueling yourself with carbohydrates, you put yourself at a higher risk of selecting for cancer. That's why many cancers are "obesity" related. This is true, but it's not the fatness that causes the cancer. It's the insulin/IGF1 that is constantly being spiked(which also causes obesity). And when you finally get a little bit of cancer, fueling it with glucose(or carbs) is like fertilizing it.