Lymphadenectomy in Early Ovarian Cancer

Inclusion Criteria: 1. Women aged 18 years to 70 years. 2. Primary diagnosis of epithelial ovarian cancer FIGO stage IA-IIA ( recevive no prior treatment or receive incomplete initial surgery)，with indications of adjuvant chemotherapy：①High-grade serous carcinoma; ②Grade 3 endometrioid carcinoma; ③Clear cell carcinoma; ④Grade 2 endometrioid carcinoma with capsule ruptured or pelvic tissues extension ⑤Low-grade serous carcinoma、Grade 1 endometrioid carcinoma and Mucinous carcinoma of the ovary with pelvic tissues extension. 3. Patients who have given their signed and written informed consent. 4. Good performance status (ECOG 0/1). Exclusion Criteria: 1. Non epithelial ovarian malignancies and borderline tumors. 2. Suspicious lymph nodes at preoperative radiological evaluation. 3. Intraoperative clinically suspicious lymph nodes (bulky nodes). 4. Secondary invasive neoplasms in the last 5 years (except synchronal endometrial carcinoma FIGO IA G1/2, non melanoma skin cancer, breast cancer T1 N0 M0 G1/2) or with any signs of relapse or activity. 5. Prior chemotherapy for ovarian cancer or abdominal/pelvic radiotherapy. 6. Diseases of the lymph system (including lymph edema of unknown origin). 7. Prior retroperitoneal lymph node dissection (systematic or sampling). 8. Any other concurrent medical conditions contraindicating surgery. 9. Pregnancy. 10. Any reasons interfering with giving of informed consent , abiding by protocol, or regular follow-up.