Back when I was doing letrozole, the docs weren't sure that Reclast or Zometa had that preventative effect. The main function at the time was to address the bone loss that resulted from the estrogen deprivation caused by the AI. Everyone I know is doing one or the other, unless they have some contraindication. At the time I was not given Reclast because there was a possible risk of exacerbating my afib, a concern that has since been disproven. I lost a lot of bone density as a result. Good idea to do if you can!