Effects of Letrozole Compared with Danazol on Patients with Confirmed Endometriosis: A Randomized Clinical Trial

Background: Letrozole is an aromatase inhibitor which can decrease estrogen production inperipheral tissues and endometriosis. Danazol, as an androgen, inhibits estrogen production inovaries and recently has been introduced as an aromatase inhibitor. This study was designed tocompare the effects of Danazol with Letrozole on endometriosis symptom relief.Materials and Methods: This study was a randomized clinical trial in which 105 patients withconfirmed endometriosis were randomly assigned to one of three groups. Group 1 received Letrozoletablets (2.5 mg/day), calcium (1000 mg/day) and vitamin D (800 IU/day). Group 2 received Danazoltablets (600 mg/day), calcium (1000 mg/day) and vitamin D (800 IU/day). Group 3 (placebo group)were assigned to take two calcium tablets daily (500 mg/tablet) and vitamin D (800 IU/day). Pelvicpain, dysmenorrhea and dyspareunia were assessed in participants at baseline and monthly duringthe study for a total of six months. Data were analyzed via SPSS version 15 software with Freidmanand Wilcoxon tests.Results: Mean age in three groups has no significant difference. Of the 105 participants who wereenrolled in this study, 38 patients were assigned to group 1 (Letrozole group), 37 patients in group 2(Danazol group) and 31 patients were placed in group 3 (placebo group). This study showed that themean scores for chronic pelvic pain, dysmenorrhea and dyspareunia for the Letrozole group wereless than the Danazol and placebo groups.Conclusion: This study showed that Letrozole can be more effective than Danazol for reducingchronic pelvic pain, dyspareunia and dysmenorrhea in patients suffering from recurrent endometriosis(Registeration Number: IRCT138812043414N1).