How quickly do colon polyps grow?

Variable: Generally we discuss polyp growth as being exponential, so that from a single cell to a polyp 1 cubic centimeter in size probably takes 2-3 years. Hyoweveer due the exponential growth they can double in size in shorter times. Some polyp types may be faster growing than others.

Usually slowly: Polyps generally grow slowly, taking years to get big enough to be visible. However, there do seem to be some that are faster growing and more aggressive. I have certainly seen them show up in less than a year after a previous colonoscopy.