How quickly can a colon polyp grow?

Hard to tell: It depends what type of polys we are referring to . There are very aggressive polyps that invariably turn in to cancer unless the whole colon is removed like familial polyposis . There are milder forms like hyperplastic polyps that grow slowly has less chance of transforming in to cancer. The growth potential of the polyps varies based on multiple factors including but not limited genetic, .

Some grow quickly.: I personally have a family history of colon cancer and had a normal colonoscopy only 2 years before i had a bleeding episode discovered to be from a cancer from a polyp in my cecum. 2 years is a short time to go from no sign of anything to developing a polyp, to having it become a cancer.