Letrozole versus dienogest in endometrioma recurrent after surgery: a randomized controlled trial

Background: Letrozole is a third-generation aromatase inhibitor. As there is aberrant aromatase production by endometriotic stromal cells and the growth and regression of endometriosis is estrogen-dependent, the use of letrozole to reduce the size and symptoms of endometrioma especially in recurrent cases is a promising medical intervention. Dienogest is a fourth-generation progestin which is being used for the treatment of endometriosis due to its antiproliferative and antiangiogenic properties on endometrial tissue. The present study was conducted to compare the effects of letrozole and dienogest on endometrioma recurrent after surgery.Methods: This randomized controlled study was conducted on 38 women having recurrence of endometrioma after surgery. They were randomly assigned to receive either letrozole (2.5 mg daily) or dienogest (2 mg once daily) for 6 months. Size of the endometrioma was measured by transvaginal ultrasound and the pain (dysmenorrhoea) was measured on a visual analog scale (VAS) of 0-10, prior to treatment and after 3 and 6 months of treatment.Results: The mean size of endometrioma was reduced from a baseline of 6.06±2.40 cm to 5.23±1.37 cm and to 4.59±1.25 cm after 3 and 6 months of treatment with letrozole. While with dienogest the reduction was from a baseline of 6.67±1.31 cm to 4.83±1.50 cm and to 3.80±1.34 cm after 3 and 6 months of treatment. The difference between the two groups was not statistically significant but dienogest yielded better result in terms of effect size. Decrease in pain (dysmenorrhoea) was highly significant with both the drugs.Conclusions: In terms of reduction of the size of endometrioma, dienogest yields better results than letrozole. Both the drugs are highly effective in alleviating pain (dysmenorrhoea).