ESR1 and endometriosis: Therefore, aromatase has been targetedfor the treatment of ER+ (estrogen receptor positive) breast cancer,especially in postmenopausal women.3 Inaddition to breast cancer, other hormone-related conditions, suchas short stature in boys,4 infertilityin men,5 and women,6 endometriosis,7 leiomyomatosis,8 and Klinefelter’s syndrome9 are increasingly being treated by administering aromataseinhibitors.