the standard of care in case of early ovarian cancer (stage I or II) is a complete surgery. This surgery includes : hysterectomy (remove of the uterus), bilateral salpingo-oophorectomy (remove of the adnexa), omentectomy (remove of the epiploon), bilateral pelvic lymphadenectomy (remove of pelvic lymph nodes) and para-aortic lymphadenectomy (remove of para-aortic lymph nodes). This procedure is diagnostic, curative and prognostic surgery. In fact, it allows us provider care giver to stratify the stage of the cancer, hence we give the appropriate adjuvant therapy.

However, this surgery, especially the extended lymphadenectomy, is associated with some risks: lymphocele, vessel injury, blood loss, morbidity, long recovery period ... In order to reduce these risks, we propose a sentinel lymph node biopsy. This intervention allows us to detect first lymph node relay whether pelvic or para-aortic.

In our study, we chose the patent blue dye as a tracer. This tracer is widely used in oncologic surgery (for example in breast cancer) and approved but not in ovarian cancer yet.

During surgery for early stage ovarian cancer, we will inject the patent blue dye on both side of the ovarian tumor. Then, we will check for first colorful lymph node, in both pelvic and para-aortic regions. We will send these dissected lymph node to pathology for analysis. Finally, we will continue the procedure as the standard of care.

Our objective is to compare the results between the sentinel lymph node and the complete lymphadenectomy and to study the technique of sentinel lymph node biopsy using the blue patent dye as tracer.

Patients, with an early-stage ovarian cancer ESOC (FIGO stage I & II), will be recruited. In our setting, the preoperative staging is based on :

• MRI finding (O-RADs classification 4 OR 5)
• Thoraco-abdominal CT scan
• Gastrointestinal endoscopy (if needed)
• Ovarian tumor biomarkers (CA 125, CA 19-9, Alpha-FP, HE4...) Or patients referred to our department for management of an ESOC with after an adnexectomy for ovarian mass.

These patients will receive a complete surgery for ovarian cancer : Peritoneal cytology, Bilateral adnexectomy, hysterectomy, pelvic lymphadenectomy, paraaortic lymphadenectomy, omentectomy and peritoneal biopsies.

Prior to the adnexectomy, surgeon will inject in subperitoneal space of the infundibular ligament (1 ml of patent blue dye: 0.5 ml in ventral and 0.5 ml in dorsal) and of the utero-ovarian ligament (1 ml of patent blue dye: 0.5 ml in ventral and 0.5 ml in dorsal). Then we will wait for 15 minutes: during which we will proceed to the adnexectomy. After 15 min, the retroperitoneal space of the pelvic and para-aortic regions was opened, and the presence of Sentinelle lymph Nodes (SLNs) was examined visually. The surgeon will record the number and location of the resected SLNs. Following the identification and removal of the SLNs, a complete systematic bilateral pelvic and para-aortic lymphadenectomy is performed. All specimen will be subject to histology analysis.

The collected data:

1. PreOperative informations:

   • Sociodemographic data : Age, Body Mass Index, Menopausal status..
   • History: Family history of cancer, Comorbidity, surgical history..
   • Ovarian tumor biomarkers
   • PreOperative imaging: MRI, CT scan, Ultrasonography
   • Presumed FIGO stage (I or II)

2. Peri-operative data:

   • SLN procedure: injection timing, Injected volume and site, Time to visual detection, site and number of detection
   • Operative complications: vessel injury, nerve injury and allergic reaction to dye

3. Pathological finding:

   • tumor characterization: type (serous, mucinous,...), grade and tumor size
   • SLN analysis: SLN frozen section, SLN final ultrastaging
   • Non-SLN status after complete lymphadenectomy
   • Final FIGO stage

4. Post-operative follow-up

   • Hospital stay duration
   • Post-operative complications (within Clavien-Dindo classification)
   • Adjuvant therapy

Inclusion Criteria:

• Age : aged 18 years-old or older
• Diagnosis: Suspected Ovarian cancer on MRI finding (O-RADs 4 or 5)
• FIGO stage: Stage I or II ( Based on MRI and scanner finding)
• Planned Procedure: Patients with planned for surgical complete stadification including pelvic and para-aortic lymphadenectomy
• Consent: Signing of the written informed consent after full information has been provided

Exclusion Criteria:

• Suspicious nodal involvement: Presence of suspicious lymph nodes on preoperative imaging (generally defined by a short-axis diameter ≥ 10 mm).
• Disease extension: Radiological or intraoperative evidence of extra-pelvic metastases or peritoneal carcinomatosis.
• Surgical history: History of lymphadenectomy, lymph node sampling, or major vascular surgery involving the aorta or the iliac vessels.
• History of radiotherapy: Patients who have previously undergone pelvic or abdominal radiotherapy.
• Allergies: Known allergy or adverse reaction to patent blue dyes.

Patient suspected with a FIGO Stage I or II ovarain cancer ( Based on MRI and scanner finding). Patients with planned for surgical complete stadification including pelvic and para-aortic lymphadenectomy.

The only data that i will share is specified in study description:

• PreOperative informations:
• Sociodemographic data : Age, Body Mass Index, Menopausal status..
• History: Family history of cancer, Comorbidity, surgical history..
• Ovarian tumor biomarkers
• PreOperative imaging: MRI, CT scan, Ultrasonography
• Presumed FIGO stage (I or II)
• Peri-operative data:
• SLN procedure: injection timing, Injected volume and site, Time to visual detection, site and number of detection
• Operative complications: vessel injury, nerve injury and allergic reaction to dye
• Pathological finding:
• tumor characterization: type (serous, mucinous,...), grade and tumor size
• SLN analysis: SLN frozen section, SLN final ultrastaging
• Non-SLN status after complete lymphadenectomy
• Final FIGO stage
• Post-operative follow-up
• Hospital stay duration
• Post-operative complications (within Clavien-Dindo)
• adjuvant therapy