There is no known cause of endometriosis. Therefore, there is no cure. Many theories have been suggested, but there is still no positive answer.
The most well-known theory is Retrograde Menstruation. When a female has a normal period the menstrual blood and endometrial tissue should flow out of the cervix and into the vagina. This theory suggests that the blood and tissue goes the wrong direction, it ends up going through the fallopian tubes. The reason this theory can’t be proven is because most women do, in fact, have retrograde menstruation. Why all women do not develop endometriosis is unknown.