“…8 Endometriosis has multifactorial causes, including retrograde menstruation, genetic and environmental factors, alteration of the immune system, and ectopic differentiation of mesenchymal stem cells. 9,10 Estrogen plays a necessary role in the pathophysiology of endometriosis, 11 since it promotes the implantation of endometrial tissue in the peritoneum, has proliferative and antiapoptotic effects in endometrial cells, and stimulates local and systemic inflammation. 12,13 On the basis of the "estrogen threshold hypothesis," complete estrogen suppression may not be needed to control endometriosis-associated pain, and estrogen may be adjusted to a level that is adequate to control pain but minimizes hypoestrogenic effects.…”