@rom828 I did not know you were premenopausal. Do your doctors recommend one or the other? The Oncotype score and risk of recurrence depend on taking Tamoxifen and I was told that an AI was slightly better, but for someone who is 43 I would rely on your docs, and get other opinions until you feel sure. I was not scared at all about Tamoxifen. At 63, I was prescribed an AI and usually people take Reclast with it for bones. I had a very individual problem in that my endocrinologist would not prescribe it due to a heart condition that has now been proven to not be a problem with Reclast. I caught up my bone density with Tymlos after letrozole finished. I thought most women your age would be taking tamoxifen. Is there a reason your docs recommended an AI? I am curious because my impression may have been mistaken.