I am suffering from Gr. IV endometreosis with adenomyosis. Undergone supra major laparoscopy surgery for excision of adhesions and endo implants on overy, bowel, etc. But after 10 months, overy is displaced and 3 cysts of 2.5-3 cms have been formed. Before that I have tried IVF but failed. Now, my Dr. has prescribed me Letrozole two times daily for 90 days. What is the role of this medicine. Further I want to know as to whether there is a need of add back therapy as i am already having osteoporosis.