Background: Endometriosis is defined as the presence of endometrial tissue (stromal and glandular) outside the normal uterine cavity. Conventional medical and surgical treatments for endometriosis aim to remove or decrease deposits of ectopic endometrium. The observation that hyperandrogenic states (an excess of male hormone) induce atrophy of the endometrium has led to the use of androgens in the treatment of endometriosis. Danazol is one of these treatments used. The efficacy of danazol is based on its ability to produce a high androgen/low estrogen environment (a pseudo menopause) which results in the atrophy of endometriotic implants and thus an improvement in painful symptoms.
Objectives: To determine the effectiveness of danazol compared to placebo or no treatment in the treatment of the symptoms and signs, other than infertility, of endometriosis in women of reproductive age.
Search strategy: The Menstrual Disorders Group search strategy was used to identify randomised controlled trials of the use of danazol in endometriosis. In addition, all reference lists of included trials were searched, and relevant drug companies were contacted for details of unpublished trials
Selection criteria: Randomised controlled trials in which danazol (alone or as adjunctive therapy) was compared to placebo or no therapy. Trials which only reported infertility outcomes were excluded.
Data collection and analysis: Only four trials met the inclusion criteria and two authors extracted data independently from these trials. All four trials compared danazol to placebo. Two trials used danazol as sole therapy and two trials used danazol as an adjunct to surgery. Although the main outcome was pain improvement other data relating to laparoscopic scores and hormonal parameters were also collected.
Main results: Treatment with danazol (including adjunctive surgical therapy) was effective in relieving painful symptoms related to endometriosis when compared to placebo. Laparoscopic scores were improved with danazol treatment (including adjunctive therapy) when compared with either placebo or no treatment. Side effects were more commonly reported in those patients receiving danazol than placebo.
Reviewer's conclusions: Danazol is effective in treating the symptoms and signs of endometriosis. However, its use is limited by the occurrence of androgenic side effects.