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

NCT ID: NCT07145827

Last Updated: 2025-09-12

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 60 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2024-01-02
• Study Completion Date: 2025-07-01

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.

Conditions

Breast Cancer; Endometrial Hyperplasia and Endometrial Cancers

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: PARALLEL
• Primary Study Purpose: PREVENTION
• Blinding Strategy: DOUBLE

Study Groups

Tamoxifen + Metformin

Participants in this arm (n=30) will continue taking the standard oncological tamoxifen dose as prescribed and receive an addition of metformin 500mg twice daily, titrated to tolerance, during the 12-month study period.

Group Type: EXPERIMENTAL

Metfomin

Intervention Type: DRUG

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

tamoxifen

Intervention Type: DRUG

Standard prescribed oncological dose.

Tamoxifen + Placebo

Participants in this arm (n=30) will continue to receive the standard oncological dose of tamoxifen as prescribed, in addition to a placebo tablet matching the shape size and color of metformin tablet twice daily during the 12 months study period; they will act as the control group.

Group Type: PLACEBO_COMPARATOR

tamoxifen

Intervention Type: DRUG

Standard prescribed oncological dose.

Placebo matching Metformin

Intervention Type: DRUG

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"

Interventions

Metfomin

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

Intervention Type: DRUG

tamoxifen

Standard prescribed oncological dose.

Intervention Type: DRUG

Placebo matching Metformin

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"

Intervention Type: DRUG

Eligibility Criteria

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

• Eligible Sex: FEMALE
• Accepts Healthy Volunteers: No

Sponsors

Uruk University

OTHER

Sponsor Role: lead

Responsible Party

Ghasak kais Abdulhussain

Lecturer in department of Pharmacology (B.Sc , M.Sc, Ph.D) / College of Pharmacy

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Ghasak Kais Abdulhussain, BSc, MSc, PhD (Pharmacology)

Role: PRINCIPAL_INVESTIGATOR

Uruk University

Locations

Baghdad Medical City / Department of Oncology

Baghdad, Baghdad Governorate, Iraq

Countries

Iraq

Other Identifiers

UU-TAM-MET-2024-01

Identifier Type: -

Identifier Source: org_study_id