Leaky Gut Syndrome:
Monsanto artificially increase the natural insecticides in plants to make them more resistant to pests.
Chemicals that are antagonistic to pests can also be antagonistic to humans.
By increasing the lectins to an unnatural degree, they make foods treated with glyphosate irritating to the intestinal villi. Continual irritation produces chronic inflammation, damage to the villi, and a porous condition in the lining, allowing partially-digested particles, especially protein fragments, to enter the blood stream, where they can produce an auto-immune reaction.
Just because a little of something once in a while is fairly harmless does not mean that a lot of it on a daily basis is good. (See: Alcohol.)
None of this has anything to do per se with cancer.
A compromised immune system has a lot to do with many cancers and other diseases.