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Effect of Metformin on Endometrial Thickness in Postmenopausal Breast Cancer Patients Receiving Tamoxifen

Effect of Metformin on Endometrial Thickness in Postmenopausal Breast Cancer Patients Receiving Tamoxifen

Status
Completed
Phases
NA
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT07145827
Enrollment
60
Registered
2025-08-28
Start date
2024-01-02
Completion date
2025-07-01
Last updated
2025-09-12

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Breast Cancer, Endometrial Hyperplasia and Endometrial Cancers

Keywords

Metformin, Tamoxifen, Breast cancer, endometrial hyperplasia

Brief summary

The goal of this clinical trial is to learn if metformin can reduce the increase in endometrial thickness caused by tamoxifen in women with estrogen-positive breast cancer taking tamoxifen for more than 1 year. It will also learn about the safety of taking metformin with tamoxifen. The main questions it aims to answer are: 1. Does metformin decrease endometrial thickness in women receiving tamoxifen? 2. What medical problems do participants have when taking metformin with tamoxifen? Researchers will compare tamoxifen plus metformin to tamoxifen plus placebo to see if metformin works to reduce endometrial thickness compared to placebo patients. Participants will: 1. Take metformin daily along with tamoxifen, or take tamoxifen with placebo. 2. Acquire baseline assessment and then visit the clinic at 3 months, 6 months, 9 months and 12 months for checkups and trans abdominal ultrasound test for endometrial thickness, and to be monitored for any side effects or complications.

Interventions

Metformin Tab. 500mg twice daily for 12 months (titrated to tolerance if needed).

DRUGtamoxifen

Standard prescribed oncological dose.

An inert, film-coated tablet identical in appearance and packaging to metformin 500 mg (same size, shape, color, coating, weight, and dosing schedule), manufactured without active ingredient using standard excipients (e.g., microcrystalline cellulose, starch/croscarmellose, povidone, magnesium stearate) and identical film coat (e.g., hypromellose, polyethylene glycol, titanium dioxide). Packaged in sealed blisters to minimize odor/taste cues. Dispensed by the investigational pharmacy per randomization; to be taken twice daily

Sponsors

Uruk University
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Outcomes Assessor)

Masking description

This is a double-blind study. Neither the participants nor the ultrasound operator assessing the primary outcome (endometrial thickness) will be aware of the treatment allocation. Study medication and placebo will be identical in appearance and packaging. Randomization codes will be securely held and only revealed after completion of data analysis, unless required for patient safety.

Eligibility

Sex/Gender
FEMALE
Healthy volunteers
No

Inclusion criteria

* Postmenopausal Female patients (amenorrhea ≥ 12 months). * Histologically proven (Estrogen-positive) breast cancer. * Completed all required surgery and/or chemotherapy (if indicated) * On adjuvant tamoxifen for at least 1 year. * Accepts to enroll in the study

Exclusion criteria

* Refusing to enroll in the study * Ongoing or History of: endometrial or ovarian malignancy * Concurrent hormonal therapy that might affect endometrial thickness * Concurrent Diabetes mellitus in which metformin is prescribed. * Known hypersensitivity or severe intolerance to metformin

Design outcomes

Primary

MeasureTime frameDescription
Change in endometrial thicknessBaseline, 3 months, 6 months, 9 months, and 12 months from enrollmentEndometrial thickness will be measured using transabdominal ultrasound (in millimeters) by a trained radiologist. The primary outcome is the difference in endometrial thickness between the metformin plus tamoxifen group and the placebo plus tamoxifen control group.

Countries

Iraq

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026