Endometrial cancer patients with histopathologic proof who are arranged to receive staging surgery are eligible. All patients will undergo surgery, including total abdominal hysterectomy, bilateral salpingo-oophorectomy, and pelvic and/or para-aortic lymph node dissection or sampling. Surgical specimens will be evaluated for tumor size, histologic grading, depth of myometrial invasion, and presence of lymphovascular emboli and lymph node metastasis. Stage will be determined using the International Federation of Gynecology and Obstetrics classification. Tumors of histologic types other than adenocarcinoma and adenoacanthoma will be excluded. The carcinomas were classified using a three-grade system: grade 1 carcinomas showed glandular formation in more than 95% of the tumor, grade 2 carcinomas showed a solid growth pattern in 5-50%, and grade 3 carcinomas showed a solid pattern in more than 50%. All of the patients who will be enrolled into this study need to sign the consent form and the study protocol will be under the approval of the Institutional Review Board of the patient's hospital.