A Randomized, Controlled Clinical Trial Comparing the Effects of Aromatase Inhibitor (Letrozole) and Gonadotropin-Releasing Hormone Agonist (Triptorelin)

Literature Review

A randomized, controlled clinical trial comparing the effects of aromatase inhibitor (letrozole) and gonadotropin-releasing hormone agonist (triptorelin) on uterine leiomyoma volume and hormonal status. Parsanezhad ME, Azmoon M, Alborzi S, Rajaeefard A, Zarei A, Kazerooni T, Frank V, Schmidt EH. Fertil Steril. 2010 January, 93(1);192-8. 

Reviewed by Dr. John Preston Parry, M.D., M.P.H. 

The authors performed an assessor blinded randomized controlled trial on how daily oral letrozole (2.5 mg) affected fibroids relative to monthly intramuscular triptorelin (3.75 mg). Over 12 weeks, there was a statistically significant decrease in fibroid volume for both arms, with a 46% decrease in the letrozole arm and a 33% decrease in the triptorelin arm, though the difference was not statistically significant in comparing the two arms. However, the trend was for letrozole to induce both a greater reduction in fibroid volume and a more rapid reduction, with 13%, 32%, and 43% reductions by weeks two, four, and six for letrozole, but only 7%, 19%, and 31% reductions by weeks two, four, and six for triptorelin. Also of note, no patients in the letrozole arm reported hot flashes, nor was there a statistically significant change in estradiol levels over the 12 weeks (66 pg/mL  64 pg/mL), but 96% of the triptorelin arm reported hot flashes and estradiol levels did drop in a statistically significant fashion (68 pg/mL  16 pg/mL). The authors conclude that though both agents may be effective in reducing fibroid volume, letrozole may be the preferred medication.

Comments by Dr. Steven R. Lindheim, M.D.

Triptorelin and letazole are effective treatments preoperatively for reducing fibroid and uterine volume. Further study defining intra and post-operative outcomes need to be addressed and a combination of a GnRH-a and SERM and SPERM may provide additive benefits.

The above review and commentary on this article were written by SRS members. Publication of these summaries does not reflect endorsement of any particular procedure or treatment. Views expressed in these summaries do not necessarily reflect the views of SRS or ASRM.


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