IRCT20140820018866N9 IRCT 2021-03-18 Tehran University of Medical Sciences Evaluation of the Protective Effect of Metformin against the Tamoxifen Induced Changes on Endometrium and Ovaries Evaluation of the Protective Effect of Metformin against the Tamoxifen Induced Changes on Endometrium and Ovaries in Women with Breast Cancer 2021-04-04 anticipated 100 Complete https://irct.ir/trial/54429 interventional Randomization: Randomized, Blinding: Triple blinded, Placebo: Used, Assignment: Parallel, Purpose: Prevention, Randomization description: The considered sample size is 100, with 50 participants in each group. The block randomization method will be designed by using "www.sealedenvelope.com". The size of blocks considered is 4. The random allocation list for patients will be solely available to the epidemiologist. To hide the random allocation process, 100 card sequences of treatments will be written accordingly, and then the cards will be placed inside sealed envelopes. A 10-digit random code will be written on each packet as the patient's identification number. When the physician announces the eligibility of a patient, the methodologist will provide the envelope, Blinding description: The physician, patient, and outcome assessor are unaware of the type of intervention. 3 ovarian cysts. Intervention 1: Intervention group: Metformin 500 mg ,oral tablets, three times a day for 6 months. Intervention 2: Control group: participants in the control group will take three placebo tablets daily for 6 months. Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is It is not yet known if there will be a plan to make this available