Alysia,
First, I would like to say I am sorry you are having this experience. My situation is similar to yours and DBJ's with chronic pouchitis treated with antibiotics. I also had suspected LGD in my colectomy path, but it was later deemed indefinite. I too need annual scopes and biopsies due to this and I seem to have them even more often due to the chronic nature of my pouchtiis combined with my stubbornness and continual attempt to get off antibiotics with little success.
When they found LGD (or what they thought) in my colon, they watched me and scoped me every 6 months. I had several clean scopes followed by one questionable, which led me to jpouch surgery. I am certain your surgeon will not want to jmp the gun on this due to the low occurrence of cancer in the jpouch, but I also thing those of us with chronic pouchitis are at a much higher risk of this occurring than jpouchers who do not have chronic pouchitis.
Have you been treating your pouchitis with medications this entire time and has your pouch ever been free of inflammation during your 16 years with it?