Sentinel lymph node (SLN) biopsy is currently used in the management of vulvar and breast cancers as well as in malignant melanoma, and is being intensively studied in patients with cervical and endometrial cancers. The role of lymphadenectomy in the surgical management of early-stage endometrial cancer is still controversial. The main reason to perform a SLN biopsy is to detect the lymph node that will be the first involved with metastatic disease in the nodal basin. The SLN biopsy is performed after the SLN is located with the use of different tracers in a concept called SLN mapping. Moreover, SLN evaluation has been reported to improve the accuracy of lymph node staging due to SLN pathologic ultrastaging, which includes multiple serial sectioning and immunohistochemical assessment. The aim of this project is to conduct a multicentre, prospective, observational trial to compare two different SLN labelling methods (radioactive tracer with/without blue dye vs. indocyanine green-ICG) in the same patient and to evaluate the unilateral detection rate, sensitivity, number of detected SLN, anatomical localisation of detected SLN and bilateral detection rate of SLN. The main aim of the trial is the comparison of SLN mapping between two SLN labelling methods in the same patient. The trial will answer a question whether a combination of labelling methods in the same patient increase importantly the sensitivity of SLN biopsy.

The trial has a high potential to reach the calculated number of cases and thus bring in evidence/data that will be essential for future management of SLN biopsies in endometrial cancer.

Inclusion Criteria:

• Histologically proven endometrial cancer (any tumour type).
• Apparent early-stage endometrial cancer with intermediate or high risk prognostic factors (deep myometrial invasion or G2/G3 disease or non- endometrioid histological type), no evidence of bulky or suspicious pelvic/para-aortic lymph nodes or distant metastases on preoperative conventional imaging studies; minimum requirement for clinical staging includes expert US or pelvic MRI for local staging and abdominal US or abdominal CT scan or PET CT for distant staging.
• Performance status ECOG: 0-1.
• Age ≥18, ≤85.
• History of second primary cancer only if more than 5 years with no evidence of disease.
• Approved and signed informed consent form to participate in the study.

Exclusion Criteria:

• Pregnancy
• Desire for fertility sparing
• History of pelvic or abdominal radiotherapy