Letrozole has caused many side effects (lack of oestrogen has a huge impact on the body) but I do think many things started with the chemo. If there had been a significant gap between treatments, I might be able to comment more but chemo seemed to upset my gastro-intestinal tract and it has never really recovered. Poor memory and concentration again started with chemo but I think have been exacerbated by AI. Extreme fatigue, likewise. My white cell count is consistently low which is what concerned me during the initial Covid outbreaks last year. How much can I attribute to chemo and how much to AI is unknowable, I think (unless I go off the Letrozole which I don't want to do).