Endometriosis is a disease characterized by the presence of fragments of the inner layer of the uterus outside their normal location, which means that parts of the endometrium colonize other organs, resulting in infiltrating lesions, bleeding and pain.

Endometriosis is a frequent gynecological disease responsible for a significant proportion of infertility and for a high incidence of dysmenorrhea as well as pelvic, abdominal and vaginal pain. In terms of incidence, endometriosis is the second most frequent gynecological disorder after leiomyomas (Jones and Jones, 1981) which are seen in 20% of women over age 35 (Conley and Lacey, 1984). Endometriosis is an inflammatory disease affecting 5 to 10% of women at reproductive age in the US.  Endometriosis is defined as the ''the presence of ectopic tissue which possesses the histologic structure and function of the uterine mucosa'' (Sampson, 1921). It is a debilitating disease which can affect women from menarche to menopause.
Endometriosis is most often seen in the abdomen, on the peritoneum, the ovaries, bowel or bladder. Less frequently, it can also be found in other organs such as the skin and lungs. Endometriosis is subject to the influence of the hormones responsible for the menstrual cycle, especially estrogens. Just as the normal uterine lining - also called "endometrium," endometriosis grows in cycles and causes bleeding and pain.
It remains unclear why endometriosis develops although it’s the most common cause of infertility (30 to 40% of patients who suffer from endometriosis are infertile).


Endometriosis and Antiestrogen


Since endometrial tissue requires estrogens for its growth and proliferation, a state of hypoestrogenism results in atrophy and regression of endometriosis as observed following natural or surgical menopause in women as well as in experimental animals (Dizerega, Barber et al. 1980). However, while it removes all estrogens in the normal human endometrium which lacks the enzymes to make estradiol, removal of ovarian estrogens does not remove all estrogens in endometriotic tissue which, contrary to the normal endometrium, can make its own estrogens. 

Treatment of Endometriosis

Principle: Maximal blockade of estrogens
Mode of administration: Combined oral and subcutaneous treatment

The diagnosis and the pain-related treatment costs associated with endometriosis were estimated at $22 billion in 2002.

Currently in Phase III of development.