Other theories
Stem cells: Endometriosis may arise from stem cells from bone marrow and potentially other sources. In particular, this theory explains endometriosis found in areas remote from the pelvis such as the brain or lungs. Stem cells may be from local cells such as the peritoneum (see coelomic metaplasia below) or cells disseminated in the blood stream (see vascular dissemination below) such as those from the bone marrow. Vascular dissemination: Vascular dissemination is a 1927 theory that has been revived with new studies of bone-marrow stem cells involved in pathogenesis. Environment: Environmental toxins (e.g., dioxin, nickel) may cause endometriosis. Toxins such as dioxins and dioxin-like compounds tend to bioaccumulate within the human body. Further research is needed but "it is plausible that inflammatory-like processes, caused by dioxin-like environmental chemicals, can alter normal endometrial and immune cell physiology allowing persistence and development of endometrial tissue within the peritoneal cavity, normally cleared by immune system cells". Müllerianosis: A theory supported by foetal autopsy is that cells with the potential to become endometrial, which are laid down in tracts during embryonic development called the female reproductive (Müllerian) tract as it migrates downward at 8–10 weeks of embryonic life, could become dislocated from the migrating uterus and act like seeds or stem cells. Coelomic metaplasia: Coelomic cells which are the common ancestor of endometrial and peritoneal cells may undergo metaplasia (transformation) from one type of cell to the other, perhaps triggered by inflammation.
Despite multiple benefits, there are lot of things to consider before using AIs for endometriosis, as it is common for them to induce functional cysts as an adverse effects. Moreover, dosages, treatment length, appropriate add-back therapies and mode of administration is still being investigated. Progesterone receptor modulators like mifepristone and gestrinone have the potential (based on only one RCT each) to be used as a treatment to manage pain caused by endometriosis. Other Medicines
Melatonin, there is tentative evidence for its use (at a dose of 10 mg) in reducing pain related to endometriosis. Opioids: Morphine sulphate tablets and other opioid painkillers work by mimicking the action of naturally occurring pain-reducing chemicals called "endorphins". There are different long acting and short acting medications that can be used alone or in combination to provide appropriate pain control. Chinese herbal medicine was reported to have comparable benefits to gestrinone and danazol in patients who had had laparoscopic surgery, though the review notes that the two trials were small and of "poor methodological quality" and results should be "interpreted cautiously" as  better quality research is needed. Serrapeptase, a Digestive enzyme found in the intestines of silkworms. Serrapeptase is widely used in Japan and Europe as an anti-inflammatory treatment. More research is needed but serrapeptase may be used by endometriosis patients to reduce inflammation. Angiogenesis inhibitors lack clinical evidence of efficacy in endometriosis therapy.