I had breast cancer and have been in remission for 2 years not, I used to take Letrozole and it caused the crown on my head and my fringe to thin really badly, since being off the tablet my hair has never grown back on top, I have tried shampoos for hair thinning and also seen a doctor, who gave me blood tests, but my results came back normal, I have now got to live with my hair really thin on top now which is a real shame, as I used to have thick hair but not anymore.