I was only on the Anestrozole a short time, maybe a few weeks, when PMR symptoms started. One of the doctors I asked about it was the radiologist who suggested that Anestrozole was probably the reason. I then contacted my oncologist who said to stop Anestrozole for two weeks. However, after the two weeks I still had the symptoms but no diagnosis. Oncologist sent me to my regular GP who took blood work and said I was just anemic, but he sent me to a neurologist suggesting that it might be something to do with the neuropathy I have from the chemo. It was the neurologist that diagnosed PMR so he sent me to the rheumatologist who immediately put me on Prednisone.I am now back on Anesterozole and have no symptoms so if the Anestrozole was the kick off it is not affecting me now. I am wondering if it is not just the total shock to my body from all the health issues I had, i.e. chemo, surgery, radiation, neuropathy, colonoscopy and all the different drugs I had to take. As they say, no one knows the cause of PMR. Maybe it is stress on the body as my husband was also going through some difficult health issues too. As far as you not having any breast tissue I remember asking my surgeon if it was best for me to have either a full mastectomy or just a lumpectomy. He told me that if I have a full mastectomy it is possible to get the cancer back along the scar tissue. That is the reason I only went for a lumpectomy. However, check with your own doctor about that.