Hi @daisies4ann I can’t answer all of your questions but I am on Letrozole for 5 years myself (over half way through) and discussed with the senior oncologist (with whom I had one phone call after six months on it) why five years not ten and, for some, why ten years and not longer. She explained that studies have found that the risk/reward algorithm swings firmly into the risk category after ten years for those without metastatic cancer. So, the significant issues that could/would be faced are osteoporosis causing breaks and impacting mobility, heart issues (apparently more women who have had BC die of heart disease than the cancer, which can be attributable to the obliteration of oestrogen) and, despite there being only a few studies on it, there is suspicion of a link between endocrine therapy and dementia. Dementia is my major concern because of family incidence and she was very cagey on the research results. A good friend of mine is currently being investigated for a decline in kidney function which appears to be due to Letrozole, she has been taken off it for at least a month to see if the eGFR rights itself but it may come to a choice between declining kidneys or risking BC recurrence if it doesn’t. So, in the spirit of “first, do no harm” the medics are loathe to continue on a treatment programme which has diminishing returns and increasing risks. If the NHS provides your prescription but your medics won’t agree to prescribe it any longer, I’m not sure that you’d have much leverage. All you can do is discuss it with your oncologist. As for alternatives, I wouldn’t know as I shall be glad to come off it in October 2027! You aren’t the first person I’ve seen raise this topic on the forum - have you tried using the search facility 
with something like “extending Letrozole beyond 10 years”? You may get some tips from there. You could also try phoning the nurses on 0808 800 6000 from 9am tomorrow as I’m sure they will have dealt with these questions before. Good luck.
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