Actively Recruiting
Letrozole for Treatment of Uterine Fibroids: A Randomized, Placebo-Controlled Trial
Led by University of California, San Francisco · Updated on 2026-05-20
140
Participants Needed
5
Research Sites
14 weeks
Total Duration
On this page
Sponsors
U
University of California, San Francisco
Lead Sponsor
E
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
Collaborating Sponsor
AI-Summary
What this Trial Is About
Researchers are evaluating the effects of letrozole compared to a placebo on symptoms related to uterine leiomyoma (fibroids) and the size of the leiomyoma and uterus. This is a phase 4, randomized, double-blinded, placebo-controlled trial aimed at understanding how letrozole influences symptom severity and quality of life in women with uterine fibroids. Participants will be randomly assigned to receive either oral letrozole 2.5 mg daily or a placebo capsule for 12 weeks, followed by 12 weeks of letrozole for those initially on placebo. The study includes two groups: one receiving letrozole throughout and the other receiving placebo followed by letrozole. Treatment effects on leiomyoma size, uterine volume, and symptoms will be closely monitored. During the study, participants will undergo evaluations of symptom severity, quality of life, fibroid volume, uterine volume, menstrual bleeding, sexual functioning, pelvic pain, urogenital distress, and blood levels of cholesterol and estradiol. Researchers will also track the frequency of hot flashes and adverse reactions over the 12-week treatment period. The total participation involves baseline and follow-up assessments to measure these outcomes and ensure safety throughout the trial.
CONDITIONS
Brief Title
Prescription of Letrozole for Uterine Myoma
Who Can Participate
Eligibility Criteria
You may qualify if you...
- At least 21 and less than 54 years of age (to focus on an adult, premenopausal population)
- Female sex, based on sex identified on their birth certificate (no other gender requirements)
- Have uterine leiomyomata that have been visualized on pelvic imaging (i.e., ultrasound or MRI) in the last 24 months
- Report symptoms associated with leiomyomata such as heavy uterine bleeding, pelvic pressure or discomfort, urinary or bowel abnormalities, or dyspareunia for the past 3 months
- Have at least moderate leiomyomata symptom burden, with UFS-QOL SSS score of 30 or higher at baseline
- Has regularly occurring menstrual periods of 4 days duration with a cycle of 21 to 38 days from the start of one menstrual period until the start of the next, by patient history for at least 3 months prior to screening
- Agree to use a non-hormonal or barrier method of contraception with any sexual activity with a non-sterile male partner during the study period (i.e., use of copper IUD is consistent with eligibility)
You will not qualify if you...
- Screening pelvic imaging indicating any leiomyomata 5 cm in maximum diameter, or uterine size 5 cm in length (equivalent to 16 weeks gestation)-note that candidates who exclusively have prior clinical pelvic imaging 12-24 months ago will be excluded if imaging includes leiomyomata 9 cm in maximum diameter, or uterine size 5 cm in length, presuming leiomyoma growth of 1 cm per year
- Screening pelvic imaging indicating only one, sole leiomyoma <2 cm in maximum diameter
- Any submucosal leiomyoma that is >50% within uterine cavity (FIGO Type 0 or Type 1 leiomyomata)
- Visit to the emergency room or hospitalization for leiomyoma symptoms in the last 12 weeks
- Leiomyomata treated by surgery, radiologic procedure in the last 12 weeks; or plans to undergo any of the above in the next 24 weeks
- Leiomyomata treated by GRNH agonist or antagonist in the last 12 weeks; or plans to use the above in the next 24 weeks
- Currently pregnant or lactating, pregnant or lactating in the past 12 weeks, or planning to become pregnant in the next 24 weeks
- Screening serum hemoglobin <8 g/dL, or history of blood transfusion in the last 12 weeks (indicating severe anemia)
- Screening cholesterol lipid panel testing showing LDL cholesterol level 5 190 mg/dL (due to rare side effects over long-term use of aromatase inhibitors in postmenopausal women)
- Screening serum estradiol level <30 pg/mL (consistent with postmenopausal status)
- Irregularly timed bleeding, including bleeding or spotting in between periods, in the past 3 months.
- History of osteoporosis (based on self-reported DEXA indicating bone mineral density Z-score < -2.0 at spine, total hip, or femoral neck; a prior fracture judged to be a fragility fracture; or self-reported use of bisphosphonates, calcitonin, calcitriol, ipriflavone, teriparatide, or denosumab for bone density loss)
- History of severe liver disease (Child Pugh Class C cirrhosis), posing safety risks for use of letrozole
- Current or prior history of breast cancer (given potential need to take letrozole for breast cancer treatment or secondary prevention)
- Screening pelvic imaging indicating an Ovarian-Adnexal Reporting and Data System (O-RADS) category 3, 4, or 5 ovarian or adnexal lesion
- Screening pelvic imaging concerning for other current cancer of the gynecologic, genitourinary or gastrointestinal system
- Prior hypersensitivity or significant adverse reaction to letrozole or any aromatase inhibitor, or to an ingredient in the placebo capsule
- Use of letrozole, other aromatase inhibitor, or selective estrogen receptor modulator (SERM) medications in the past 4 weeks, or existing plans to initiate one of these in the next 24 weeks
- Use of oral, vaginal, or topical exogenous estrogen, progestin, or androgen therapy in the past 4 weeks; or injectable forms of the above in the past 12 weeks; or plans to initiate any of the above in the next 24 weeks
- Use of medications with potential unsafe interactions with letrozole in the past 4 weeks (methadone, levomethadone, nintedanib, thalidomide), or plans to initiate these in the next 24 weeks
- Any condition that, in the opinion of the investigators, would interfere with ability to complete study procedures, including acute or uncontrolled mental health condition, substance abuse, or inability to complete procedures in English (or Spanish, for sites that offer study assessments in Spanish)
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - 12 weeks
Participants receive oral letrozole 2.5mg daily or placebo for 12 weeks to treat uterine fibroids.
Visits at baseline and during treatment as scheduled by the study
Trial Site Locations
Total: 5 locations
1
University of California, Los Angeles
Los Angeles, California, United States, 90095
Actively Recruiting
2
University of California, San Francisco
San Francisco, California, United States, 94115
Actively Recruiting
3
Mayo Clinic
Rochester, Minnesota, United States, 55905
Actively Recruiting
4
University of Mississippi Medical Center
Jackson, Mississippi, United States, 39216
Actively Recruiting
5
Duke University
Durham, North Carolina, United States, 27710
Actively Recruiting
Research Team
S
Study Coordinator
L
Lisa Abinanti
How is the study designed?
Study Type
INTERVENTIONAL
Masking
TRIPLE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
TREATMENT
Number of Arms
2
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