Letrozole pretreatment prior to medical termination of pregnancy: a systematic review.

OBJECTIVE: The purpose of this systematic review was to evaluate the efficacy of pretreatment with letrozole prior to either a first- or second-trimester medical termination of pregnancy.

STUDY DESIGN: We searched letrozole, femara, aromatase inhibitors, abortifacient agents, termination of pregnancy and labor induction in MEDLINE, EMBASE, Cochrane Database, Google Scholar and PubMed from inception of each database until September 2015 with no language limitation. A systematic review of all randomized controlled trials (RCTs) was performed where women received either letrozole and misoprostol or placebo and misoprostol for termination of pregnancy. The primary outcome was complete abortion rate, defined as complete evacuation of the products of conception from the uterus. Relative risk with 95% confidence intervals was used to report data.

RESULTS: Our systematic review identified 7 studies; 4 RCTs were included in the review. Two RCTs evaluated terminations of pregnancy up to 9 weeks' gestation, while 2 evaluated terminations over 9 weeks' gestation. For each gestational age group, one trial supported an increase in complete abortion rate, while the other showed no difference, with letrozole and misoprostol compared with placebo and misoprostol. Time-to-abortion interval for terminations up to 9 weeks' gestation was not improved with the addition of letrozole to misoprostol. For terminations over 9 weeks' gestation, one trial supported and one trial refuted a decrease in time-to-abortion interval with letrozole and misoprostol. Similarly, for each gestational age group, one study supported a decrease and one study showed no difference in rate of dilation and curettage (D&C) with letrozole and misoprosol. Medication side effects were similar between both treatment groups. There was significant heterogeneity between the trials, and therefore, the results were not meta-analyzed.

CONCLUSIONS: Some studies and trials report better outcomes (i.e., complete abortion rates, time-to-abortion and D&C rates) in women exposed to letrozole and misoprostol compared to placebo and misoprostol, while other trials demonstrate no difference. Further research exploring letrozole pretreatment prior to medical abortion is required.

IMPLICATIONS: This systematic review demonstrated that a combination of letrozole and misoprostol increased the rate of complete abortion compared to misoprostol alone in some studies but not in others; additional well-designed RCT's are needed.