Gonadotropin-releasing Hormone Agonist (GnRHa) Plus Letrozole In Young Women With Early Endometrial Cancer

Inclusion Criteria: * Consent informed and signed * Primarily have a confirmed diagnosis of early-stage endometrial cancer (endometrioid, grade I, without myometrial inva- sion) ) based upon endometrial biopsy, diagnostic curettage or hysteroscopy * No signs of suspicious myometrial invasion or extrauterine metastasis by enhanced magnetic resonance imaging (MRI), enhanced computed tomography (CT) or transvaginal ultrasonography (TVUS) * Have a strong desire for remaining reproductive function or uterus * Have good compliance and follow-up conditions, and patients are willing to follow up in Obstetrics and Gynecology Hospital of Fudan University in time Exclusion Criteria: * Pathologically confirmed as endometrial cancer with suspicious myometrial invasion or extrauterine metastasis * Recurrent endometrial cancer * Combined with severe medical disease or severely impaired liver and kidney function * Patients with other types of endometrial cancer or other malignant tumors of the reproductive system; patients with breast cancer or other hormone- dependent tumors that cannot be used with progesterone * Those who require hysterectomy or other methods other than conservative treatment with drugs * Known or suspected pregnancy * Contraindication for Medroxyprogesterone Acetate, Megestrol Acetate, Triprorelin Acetate, Letrozole or pregnancy * Hormone treatment within 3 months before entering the trial; * Acute severe disease such as stroke or heart infarction or a history of thrombosis disease * Smoker(\>15 cigarettes a day)