Clinical Effects of Metformin on Fertility-sparing Treatment for Early Endometrial Cancer

Inclusion Criteria: * Endometrial cancer radiologic International Federation of Obstetrics and Gynecology (FIGO) stage IA patients * Endometrioid endometrial cancer patients * FIGO cellular differentiation grade 1 patients * Patients who wish to preserve fertility * Patients who understand that the recommended treatment of endometrial cancer is surgical treatment even in early stages, but still wish to preserve fertility and avoid surgical treatment * Patients who have good performance status (Eastern Cooperation Oncology Group (ECOG) performance score equal to or greater than 3) * Patients who are not contraindicated to the progestin therapy * Patients who are not contraindicated to the use of metformin Exclusion Criteria: * Patients who have already received chemotherapeutic or radiotherapeutic treatments for endometrial cancer * Patients whose disease is already advanced and not indicated for fertility-sparing treatment * Patients whose tumor cellular differentiation grade is greater than FIGO grade 1