Sentinel Lymph Node Mapping and Biopsy for Endometrial Cancer at Early Stage with Laparoscopy

Podsumowanie

This protocol describes the identification and resection of sentinel lymph nodes to make the operation as easy and minimally invasive as possible.

Streszczenie

Sentinel lymph node (SLN) mapping and biopsy is a promising technique for visualizing and evaluating lymph node status in cancer. This approach has been recommended for low-risk endometrial cancer (EC) patients by authoritative international guidelines, but it has not been performed broadly in China and worldwide. This work aims to describe detailed SLN mapping and biopsy procedures to promote the clinical application. SLN mapping and postoperative pathologic ultrastaging were conducted in a patient with low-risk EC using indocyanine green (ICG) dye to track the SLNs under laparoscopy and resecting them completely for ultrastaging. In conclusion, this protocol describes details of ICG injection, and SLN mapping and biopsy in EC patients based on the experiences gained during clinical practice.

Wprowadzenie

Endometrial cancer (EC) is one of the most common diseases in gynecological oncology, and its incidence is rising^1,2. Surgery is the first-line treatment for early-stage EC^3,4. The evaluation of lymph node metastasis is an essential part of surgical staging in EC. The Gynecologic Oncology Group (GOG) study 33 demonstrated that lymph node metastases are associated with poor prognosis⁵.

As a new and essential technique for evaluating lymph node metastasis, sentinel lymph node (SLN) mapping and biopsy have emerged in recent years and have been recommended to be employed for patients with apparent uterine-confined EC according to the National Comprehensive Cancer Network (NCCN) guidelines for uterine cancer^6,7,8,9,10. SLN mapping has also been extensively applied in tumors such as breast cancer¹¹, lung cancer¹², thyroid cancer¹³, and melanoma¹⁴. Pathologic ultrastaging has achieved good performance in colorectal and gynecological cancer^15,16,17 and is recommended by the authoritative European guidelines¹⁸. Although principles of SLN mapping for EC staging have been provided in international guidelines^10,19, there are no detailed manipulations of surgery in other present works.

This work presents the protocol for detailed SLN mapping and biopsy with ICG in a 28-year-old female who had been clinically diagnosed with early-stage EC, thus, improving and promoting the diagnosis of patients.

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Protokół

All surgery procedures related to the patient described here were approved by the Ethics Committees of Obstetrics & Gynecology Hospital of Fudan University in Shanghai, China. Informed consent was acquired from the patient.

1. Indications for SLN mapping with ICG in EC patients

1. Ensure that patients are clinically diagnosed with primary EC confined to the uterus with low-risk factors (grade 1 or 2 endometrioid carcinomas, pre-surgical endometrial lesion ≤2 cm, and myometrial invasion <50%).
2. Ensure that patients are not allergic to the developer (ICG).
3. Ensure that patients have not experienced retroperitoneal lymph node dissection for any reason before the disease.
4. Ensure that the patients understand the SLN surgical procedures and have signed the surgical consent forms.
5. Ensure that the patients cannot perform systematic lymphadenectomy but SLN mapping for surgical staging for any reason.
6. Ensure that the patients are enrolled in the clinical trial into the SLN mapping group if they are with intermediate-high risk EC.

2. Patient preparation

1. Preoperative bowel preparation
   1. Provide laxatives for bowel preparation and enema to patients who have undergone multiple pelvic and abdomen surgeries.
      NOTE: Intestinal preparation is not required for patients without bowel surgery history.
2. Preoperative diet preparation
   1. Avoid solid food for 8 h before the operation, prevent a semi-liquid diet for 6 h before the procedure, and stop drinking for 2 h before the procedure.
3. Anesthesia
   1. Use intravenous agents (e.g., propofol) to produce unconsciousness and add some neuromuscular blockers by inhalation or intravenous routes to achieve the needed depth of anesthesia. Use a combination of administrations for anesthetic maintenance to ensure the patient to be unconscious and fully relaxed with stable vital signs throughout the operation.
      NOTE: The usage of anesthetics will be following the rules of the anesthesiology department of each center.
4. Position
   1. Once the patient is anesthetized, allow the patient to be in the lithotomy position with Trendelenburg position.
5. Prepare the skin at the surgical site. Perform skin preparation with an antiseptic preparation (e.g., povidone-iodine) in an organized fashion from the intended site of the incision radiating out to the edges of the intended area of skin exposure, with the upper boundary of flat xiphoid process, side borders of mid-axillary lines, and lower boundary of the upper thigh (Figure 1).

3. Fluorescent dye preparation

1. Indocyanine green (ICG) preparation
   1. Dissolve 25 mg of ICG into 20 mL of sterile water for a final concentration of 1.25 mg/mL and shake gently.

4. ICG injection

1. Use a 2 mL syringe (with the needle size of 0.6 mm x 32 mm TW LB) to inject 0.5 mL of the prepared ICG at 3 o'clock and 9 o'clock of the ectocervix at the superficial (2-3 mm) and deep (1-2 cm) cervix, respectively (Figure 2).
   ​NOTE: In some cases, the ectocervix positions of 6 and 12 o'clock can also be selected. ICG should be avoided when injected into Nessler's cyst.

5. Intraoperative SLN identification

1. Preparation before development
   1. Grasp the skin around the umbilicus with two towel forceps to elevate the abdominal wall. Make an incision of about 10 mm wide in the skin of the umbilicus and through the fascia and peritoneum.
   2. Insert a 10 mm trocar through the umbilicus, producing the pneumoperitoneum with intraperitoneal pressure of about 13-14 mmHg. Insert a laparoscope (with light source and cameras) via the trocar.
   3. Make three other small incisions of ~5 mm wide in the lower abdomen and insert 5 mm trocars through the abdominal wall into the cavity. Insert instruments for manipulation via the other three 5 mm trocars (Figure 1).
   4. Identify the fallopian tubes under laparoscopy. Grasp and elevate the tubes close to fimbriae and tie a ligature around the tube with a 2-0/T silk suture.
      NOTE: This step is used to prevent endometrial tumor cells from entering the abdominal cavity along the fallopian tubes from the uterine cavity.
   5. Take the peritoneal washings with 100 mL of normal saline before any significant handling or manipulation of the uterus. Collect the washing fluid for cytology.
   6. Open the fluorescence mode of the endoscopic fluorescence imaging system (see step 5.2). Lift unilateral pelvic infundibulum ligament and uterus to reveal the lateral peritoneum and look for the fluorescence lymphatic vessels.
      ​NOTE: If there are no fluorescence lymphatic vessels identified, it is allowed to inject ICG repeatedly.
2. SLN mapping
   1. Endoscopic fluorescence imaging system preparation (PINPOINT).
   2. Adjust the fluorescence mode to near-infrared laser (excitation light, 805 nm) for the best field of view.
      NOTE: The endoscopic fluorescence imaging system has several modes, such as HD (High definition) white light, SPY fluorescence, PINPOINT fluorescence, and SPY CSF mode, and the surgeon can switch to another mode if necessary.
3. Identify SLNs under a fluorescence laparoscopy.
   1. Hold an ultrasonic scalpel and toothless forceps with each hand (performed by the surgeon).
      NOTE: The assistant grasps toothless forceps to cooperate with the surgeon.
   2. Lift and open the peritoneum, separate the sub-peritoneal fat and connective tissues to reveal the necessary structures, including the ureter, internal iliac vessels, and obturator nerves according to the indication of green fluorescence lymphatic lines, as well as to protect them from injury.
      NOTE: An ultrasonic scalpel with activation is used to cut the tissues, while an inactivated scalpel can be used for blunt dissection.
   3. Observe the SLNs covered by the peritoneum about 5-10 min after ICG injection.
      ​NOTE: Typically, SLNs present along with the fluorescence lymphatic vessels from both sides of the cervix to at least the height of the common iliac blood vessel. Occasionally, the SLNs emerge beside the abdominal aorta. PINPOINT equipment has multiple modes, including white light, fluorescence, and black and white modes. Switching between multiple modes helps to determine the location of SLNs.

6. Intraoperative SLN biopsy

1. Locate the SLN, the first mapped lymph node along the drainage from parametrium in each hemi-pelvis, and use multiple modes to confirm it. Fully expose the SLNs for complete resection (Figure 3).
2. Grasp and elevate the SLN by toothless forceps and perform a complete resection of the lymph node along the periphery of the lymph node in white light.
   NOTE: Avoid lymph node damage, which might cause contamination with tumor cells.
3. Place the removed SLNs in the obturator fossa or put them into a small, simple bag. After the uterus is completely removed and taken out through the vagina, bilateral SLNs are taken out entirely through the vagina rather than through the 5 mm trocar opening to avoid fragmentation.
4. Send the removed lymph nodes to the pathology department for pathological ultrastaging.
5. During the operation, resect the enlarged or suspicious lymph nodes simultaneously and send them for pathological examination.
6. Record the locations of SLNs on standardized intraoperative data collection forms.
7. If SLN mapping fails on one or both sides, perform side-specific lymphadenectomy according to the NCCN guidelines.
   NOTE: If there is no fluorescent node in the hemipelvis, continue to seek the mapped node along the lymphatic vessels until the para-aortic region due to the possibility of mapping in unexpected locations. A failed SLN mapping on either side means that any fluorescent green node is not visible with or without fluorescent green lymphatic vessels under the fluorescence laparoscope system on either side of the pelvis and para-aortic region.
8. Perform a total hysterectomy plus bilateral salpingectomy.
   ​NOTE: Since this was a 28-year-old patient with early-stage endometrioid cancer who had a strong desire for fertility preservation and normal-appearing ovarian cancer and had no apparent family history of breast/ovarian cancer or Lynch Syndrome, ovarian preservation could be considered.
9. Indwell a drainage tube for potential residual fluid in the pelvis.
10. Remove the laparoscope and release the gas from the abdomen. Close the incisions in the umbilicus and lower abdomen with a single stitch by 2-0/T silk suture.

7. Postoperative SLN ultrastaging²⁰

1. Cut the SLN along the maximum diameter and micro-sectioned 50 µm apart to get three hematoxylin-eosin (H&E) slides and one immunohistochemistry (IHC) slide with anti-cytokeratin antibody (AE1/AE3).
   NOTE: Ultrastaging entails thin serial sectioning of the gross SLN. Cytokeratin IHC is not essential. No standard protocol is for ultrastaging.
2. Lymph node metastases were described as macrometastases (>2 mm), micrometastases (0.2-2.0 mm), or isolated tumor cells (ITCs) according to the classification of the American Joint Committee on Cancer (AJCC)²¹.
3. Report the postoperative pathology with details about the tumor size, histologic type and grade, myometrial invasion, lymphovascular space involvement, cervical stromal involvement, number and status of per lymph nodes, and the cytology of peritoneal washings.

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Wyniki

The patient in the present case was a 28-year-old female with irregular vaginal bleeding for 2 years, and she was diagnosed with an abnormality of the endometrium 4 months ago. Transvaginal ultrasound examination revealed a heterogeneous endometrial thickness with an adnexal mass. Abdominopelvic magnetic resonance imaging (MRI) demonstrated a 51 mm x 56 mm x 88 mm mass with a clear boundary within the uterine cavity under a high T2WI signal in a local hospital. Then, she was evaluated by hysteroscopy, and the endometria...

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Dyskusje

SLN mapping and biopsy is a more selective and tailored lymph node dissection approach that has been applied in the clinic for nearly 20 years. In the field of EC, SLN mapping and biopsy have been increasingly recommended by several guidelines due to their high diagnostic efficiency in early-stage EC, achieving overall and bilateral detection rates of 89%-95% and 52%-82%, respectively, with a sensitivity of 84%-100% and negative predictive value of 97%-100%²². The present study reports a typical E...

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Materiały

Name	Company	Catalog Number	Comments
2-mL syringe	Becton, Dickinson and Company, USA	301940
Coagulation forceps	Shanghai Medical Instrument (Group) Co., Ltd. Surgical Instrument Factory	D0A010
Fluorescence microscope	Olympus	IX73
Harmonic scalpel	Soering GmbH	SONOCA190
Hematoxylin-eosin staining	Beyotime Biotechnologies Corporation,CN	C0107
Immunohistochemical cytokeratin staining	MXB Biotechnologies Corporation, CN	Kit-0020
Indocyanine green (ICG)	Dandong Medical Innovation Pharmaceutical Corporation.	3599-32-4
Pararaffin	Sangon biotech Co., Ltd.	A601889
Pinpoint Endoscopic Fluorescence Imaging system	Novadaq Technoloies Bonita, Springs, FL	NA
Propofol Injection	Fresenius Kabi Deutschland GmbH D-61346 Bad Homburg v.d.H., Germany	H20030124
Silk Braided non-absorbable suture	Shanghai Ethicon	SA854G
Silk thread	Beijing AKIN AIEN International Medical Technology Co.,Ltd.	VCPP71D
Suction-Irrigation Tube	Shanghai SMAF	YX980D
Toothless forceps	Shanghai Medical Instrument (Group) Co., Ltd. Surgical Instrument Factory	J41010
Trocar	ETHICON Co,. Ltd, USA	B10LT, B5LT