burritos

While cancer science is still emerging, the hallmarks of most cancers involve:

It's unlikely that just one gene or one insult causes all this. But dysregulation of energy(burning carbs vs burning fat) is often cited as a key step. When you induce glycolysis(sugar burning) over fat metabolism, you accumulate mitochondria impairment. ROS(reactive oxygen species, also known as 'oxidative stress') occurs primarily at the level of the mitochondria, specifically at the electron transport system. When you have healthy metabolism, ROS acts to mediate insulin signaling. Healthy metabolism will control hunger and prevents the VMH(Ventromedial Hypothalmus) from encouraging foraging/or what we recognize as over eating. "Yum, you can't just eat one cheetoh". Excess ROS occurs with chronic overeating(also known as energy toxicity). ROS unchecked over years can accumulate a multitude of necessary specific DNA insults which ultimately results in the above winning cancer lottery numbers to get the losing ticket.

So I agree with your statement that eating/or not eating one specific thing could cause/stop cancer, including fiber. If you're eating fiber/whole foods, it's possible you're not eating processed foods in abundance at the same time. But the general hypothesis that we're all 1 or 2 genetic errors from cancer is flawed. Yes you need the genetic errors. Some might be inherited. But I believe the dysfunction in mitochondria gives you the DNA damaging mechanism necessary to keep rolling the dice till you hit all the losing numbers.