Megestrol Acetate Compared With Megestrol Acetate and Metformin to Prevent Endometrial Cancer

Inclusion Criteria: * Participants with endometrial intraepithelial neoplasia (EIN) on an endometrial biopsy or dilation and curettage specimen will be eligible. Participants diagnosed with EIN bordering on, approaching or suspicious for endometrial adenocarcinoma are allowed. Participants can be diagnosed with EIN at any time in the three months prior to enrollment. Other commonly used pathologic terms for EIN, such as complex atypical hyperplasia and atypical hyperplasia will also be eligible * Age \>= 18 years-old. EIN is almost exclusively an adult condition. Because no dosing or adverse event (AE) data are currently available on the use of megestrol acetate in participants \< 18 years of age, children and adolescents are excluded from this study * Eastern Cooperative Oncology Group (ECOG) performance status =\< 2 (Karnofsky \>= 60%) * Total bilirubin =\< 1.5 x institutional upper limit of normal * Aspartate aminotransferase (AST) (serum glutamic-oxaloacetic transaminase \[SGOT\])/alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase \[SGPT\]) =\< 3.0 x institutional upper limit of normal * Creatinine =\< 1.5 x institutional upper limit of normal * Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial * For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicat…