It’s hard when there is no research - I’m on Letrozole and research (one major study but a really large number of participants) does indicate that ten years are better than five. If you are handling it well, why not, but if you are having troublesome side effects, that’s a different matter. I’m at Year 8 too, monitoring the side effects and if nothing gets worse, I will go to ten but it depends - any major problem and I’ll work on the ‘eight is better than five’ theory even though no-one so far as I know has done that specific bit of research! Best wishes.