@bd2486 I had a 5% drop in bone density on letrozole, a similar drug, the first year and then a 2% drop each year for the next 4 years. This was similar to my pattern at menopause: a bigger drop the first year and then a stable but continued drop from then on. Most people take Reclast or Zometa during treatment to prevent this, but my endo doc was concerned about certain other health issues and did not prescribe.

@ginip as you know osteoporosis does not have symptoms. Knee pain might indicate osteoarthrtis but not osteoporosis. Nevertheless, without bone meds, aromatase inhibitors are thought to pose risks of bone density loss. Of course it depends too on how our bones were to start with: I already had pretty bad osteoporosis when I went on letrozole! (Now I am finished with Tymlos and bones are better than they were before cancer.)