The primary aim of this trial is to ascertain whether or not systematic pelvic and para-aortic lymphadenectomy (LNE) does have a significant impact on overall survival (OS) in patients with endometrial cancer (EC) FIGO Stages I or II and high risk of recurrence. Secondary aims will be to evaluate the effect of LNE on disease free survival (DFS) and quality of life, as well as the complications and side effects of LNE and the number of resected lymphnodes. 640 patients with histologically confirmed EC with high risk of recurrence (stage pT1b - pT2, all histological subtypes; pT1a, G3 endometrioid or serous or clear cell EC or carcinosarcomas) will be randomized. In Arm A, a total hysterectomy and bilateral salpingo-oophorectomy and in case of serous or clear cell EC additionally an omentectomy will be performed. In arm B in addition a systematic pelvic and para-aortic LNE up to the level of the left renal vein will be performed.

Inclusion Criteria:

1. histologically confirmed EC of clinical stages T1b and T2 (all histological types) and stage T1a G3 type 1 (endometrioid, endometriod with squamous differentiation, mucinous) or type 2 tumors (any percentage of serous or clear cell component) or carcinosarcoma
2. a) no previous surgery concerning EC (primary surgery) or b) surgery after hysterectomy (e.g. for presumed low risk endometrial cancer) is allowed within 8 weeks after hysterectomy if no LNE was performed (secondary surgery)
3. absence of bulky lymph nodes
4. performance status ECOG 0-1
5. age 18 - 75 years
6. written informed consent
7. adequate compliance

Exclusion Criteria:

1. stage pT1a, G1 or G2 tumors of type 1 histology
2. sarcomas (except for carcinosarcoma = malignant mixed Müllerian tumor)
3. EC of FIGO stages III or IV (except for microscopical lymph node metastases)
4. evidence of extrauterine disease by visual inspection
5. recurrent EC
6. preceding chemo-, radio, or endocrine therapy for EC
7. any concomitant disease not allowing surgery including lymphadenectomy and/or chemotherapy
8. any medical history indicating excessive peri-operative risk
9. any current medication containing considerable surgical risk (e.g. bleeding: due to oral anticoagulating agents)
10. any known disorder or circumstances making participation in trial and follow-up questionable. Insufficient compliance is expected.
11. patients with second malignancies if disease or treatment might have an impact on the patient's prognosis
12. known HIV-infection or AIDS
13. simultaneous participation in other clinical trials if not permitted by the steering committee (translational or QoL studies not interfering with the objectives of ECLAT are allowed)