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

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

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"