I am a 50yr old woman and am 2.5 years post-op stage 2, hormone receptor positive breast cancer. I had no chemo, only accelerated radiation treatment following surgery. Because of a total hysterectomy 10 years ago and now being deprived of any hormones, I take a myriad of medications including- only recently (4 weeks ago) replacing Tamoxifen with Arimidex. I have always had strong thick fingernails. Within the last 2 weeks my nails have ridges and have begun to flake and split and are very thin. I keep them at a reasonable length and healthy, and get manicures on occasion. They are so thin my 16yr old daughter noticed the dramatic change. My diet and health in general are about the same as before, so what is it? Obviously I should continue the Arimidex as prescribed, but I want to know what is going on? Anyone in a similar pickle?