Robotic sentinel lymph node (SLN) mapping in endometrial cancer: SLN symmetry and implications of mapping failure

Sentinel Lymph Node Mapping by Retroperitoneal vNOTES for Uterus-Confined Malignancies: A Standardized 10-Step Approach

(1) Background: Sentinel lymph node (SLN) mapping represents an accurate and feasible technique for the surgical staging of endometrial and cervical cancer. This is commonly performed by conventional laparoscopy or robotic-assisted laparoscopy, but in recent years, a new retroperitoneal transvaginal natural orifice transluminal endoscopic surgery (vNOTES) approach has been described and developed by Jan Baekelandt. This technique provides easy visualization of lymphatic afferent vessels and pelvic lymph nodes, early SLN assessment, and a coherent mapping methodology following the lymphatic flow from caudal to cranial. However, only a few publications have reported it. Following the IDEAL (Idea Development Exploration Assessment Long-term follow-up) framework, research concerning this technique is in Stage 2a, with only small case series as evidence of its feasibility. Its standardized description appears necessary to provide the surgical homogeneity required to move further. (2) Methods: Description of a standardized approach for retroperitoneal pelvic SLN mapping by vNOTES. (3) Results: We describe a 10-step approach to successfully perform retroperitoneal vNOTES SLN mapping, including pre-, intra-, and postoperative management. (4) Conclusions: This IDEAL Stage 2a study could help other surgeons approach this new technique, and it proposes a common methodology necessary for evolving through future IDEAL Stage 2b (multi-center studies) and Stage 3 (randomized controlled trials) studies.

Anatomical Distribution of Sentinel Lymph Nodes Harvested by Retroperitoneal vNOTES in 34 Consecutive Patients With Early-Stage Endometrial Cancer: Analysis of 124 Lymph Nodes

STUDY OBJECTIVE

To determine the anatomical distribution of sentinel lymph nodes (SLNs), the overall, unilateral, and bilateral detection rates, and the bilateral SLN concordance in patients with endometrial cancer (EC) mapped through a retroperitoneal transvaginal natural orifice transluminal endoscopic surgery (vNOTES) approach.

DESIGN

Prospective single-center observational study.

SETTING

Swiss teaching hospital.

PATIENTS

Patients with EC or endometrial complex atypical hyperplasia who had undergone surgical staging with SLN mapping by a retroperitoneal vNOTES approach between October 2021 and November 2023.

INTERVENTIONS

Patients were placed in a horizontal dorsal lithotomy position under general anesthesia, and indocyanine green (ICG) was injected into the cervix. Access to the retroperitoneal space was achieved through vaginal incisions. A 7 cm GelPoint V-Path Transvaginal Access Platform was used as a vNOTES port, and CO2 was insufflated to expand the retroperitoneal space. The pelvic retroperitoneal space was inspected for ICG uptake by lymph nodes. After identification, SLNs were removed and sent for definitive histological examination.

MEASUREMENT AND MAIN RESULTS

A total of 34 patients were included in this study; 33 (97.1%) had a successful procedure (unilateral or bilateral mapping), and 1 (2.9%) had failed mapping. A total of 124 SLNs were identified and removed. SLNs were observed in the obturator region (81.5%), the external iliac region (10.5%), the internal iliac region (4.8%), and the common iliac region (3.2%). Similar proportions were observed on both pelvic sides. No SLNs were detected in other regions. The SLN locations were symmetrical in 22/31 (71.0%) patients. SLNs were negatives in 120 cases (96.8%), while 2 lymph nodes (1.6%) presented isolated tumor cells, and 2 others (1.6%) presented macrometastases.

CONCLUSION

We report anatomical distributions and detection rates for SLNs mapped by retroperitoneal vNOTES. Our results suggest substantial differences in the localization of SLNs compared to those reported for laparoscopic mapping.

The added value of SLN mapping with indocyanine green in low- and intermediate-risk endometrial cancer management: a systematic review and meta-analysis

OBJECTIVE

The aim of this study was to assess the SLN detection rate in presumed early stage, low- and intermediate-risk endometrial cancers, the incidence of SLN metastases, and the negative predictive value of SLN mapping performed with indocyanine green (ICG).

METHODS

A systematic review with meta-analyses was conducted. Study inclusion criteria were A) low- and intermediate-risk endometrial cancer, B) the use of ICG per cervical injection; C) a minimum of twenty included patients per study. To assess the negative predictive value of SLN mapping, D) a subsequent lymphadenectomy was an additional inclusion criterion.

RESULTS

Fourteen studies were selected, involving 2,117 patients. The overall and bilateral SLN detection rates were 95.6% (95% confidence interval [CI]=92.4%-97.9%) and 76.5% (95% CI=68.1%-84.0%), respectively. The incidence of SLN metastases was 9.6% (95% CI=5.1%-15.2%) in patients with grade 1-2 endometrial cancer and 11.8% (95% CI=8.1%-16.1%) in patients with grade 1-3 endometrial cancer. The negative predictive value of SLN mapping was 100% (95% CI=98.8%-100%) in studies that included grade 1-2 endometrial cancer and 99.2% (95% CI=97.9%-99.9%) in studies that also included grade 3.

CONCLUSION

SLN mapping with ICG is feasible with a high detection rate and negative predictive value in low- and intermediate-risk endometrial cancers. Given the incidence of SLN metastases is approximately 10% in those patients, SLN mapping may lead to stage shifting with potential therapeutic consequences. Given the high negative predictive value with SLN mapping, routine lymphadenectomy should be omitted in low- and intermediate-risk endometrial cancer.

A Model to Identify Candidates for Lymph Node Dissection Among Patients With High-Risk Endometrial Endometrioid Carcinoma According to Mayo Criteria

Background

The Mayo criteria are the most widely accepted algorithm for predicting the risk of lymph node metastasis in endometrial endometrioid carcinoma (EEC). However, the clinical value of these criteria in high-risk patients is limited and inconclusive.

Methods

A total of 240 patients with EEC meeting the Mayo high-risk criteria between January 1, 2015, and December 31, 2018 were included in our study. We retrospectively collected the laboratory reports, basic clinical information, clinicopathological and immunohistochemistry (IHC) findings, and the sequences of molecular pathological markers of these patients. A nomogram for predicting the likelihood of positive lymph node status was established based on these parameters.

Results

Among the 240 patients, 17 were diagnosed with lymph node metastasis. The univariable analyses identified myometrial invasion >50%, aberrant p53 expression, microsatellite instable (MSI), and cancer antigen 125 (CA125) ≥35 U/ml as potential risk factors for lymph node metastasis. The multivariable analyses showed that aberrant p53 expression, MSI, and CA125 ≥35 U/ml were independent predictors of lymph node metastasis. The area under the curve (AUC) for the nomogram was 0.870, as compared to 0.665 for the Mayo criteria.

Conclusions

Our novel prediction model effectively identifies patients at high risk for lymphatic metastasis. This model is a promising strategy for personalized surgery in patients with high risk according to the Mayo criteria.

Sentinel Node Biopsy for Endometrial Cancer by Retroperitoneal Transvaginal Natural Orifice Transluminal Endoscopic Surgery: A Preliminary Study

Objective

The primary objective was to determine the intraoperative and postoperative surgical complications of sentinel lymph node biopsy (SLNB) by retroperitoneal transvaginal natural orifice transluminal endoscopic surgery (vNOTES). The secondary objective was to assess the feasibility of this surgical technique.

Methods

This was a descriptive study realized in a non-university hospital in Switzerland. Seven patients with endometrial cancer or endometrial complex atypical hyperplasia underwent surgical staging with SLNB by retroperitoneal vNOTES using an indocyanine green-based near-infrared fluorescence imaging technique (October 2021-February 2022).

Results

The median operative time was 113 (81-211) minutes. The median estimated blood loss was 20 (20-400) mL. The overall bilateral detection rate was 100% (7/7). Upon histopathological examination, 5 patients presented an endometrial adenocarcinoma, and we found endometrial complex atypical hyperplasia in 2 cases. We successfully completed all procedures without significant intraoperative complications, but 1 case required conversion to conventional laparoscopy. The median postoperative stay was 2 (2-4) days, and we observed no postoperative complications during this period. We observed 1 case of postoperative deep vein thrombosis and an asymptomatic vaginal vault hematoma in the same patient.

Conclusions

Our preliminary study suggests that retroperitoneal vNOTES could be a feasible, safe, and valuable approach to perform SLNB in endometrial cancer. However, strong evidence of its feasibility, the effective benefits, and the long-term oncological outcomes is needed before expanding the use of vNOTES in endometrial cancer outside study settings.

Sentinel node biopsy for diagnosis of lymph node involvement in endometrial cancer

BACKGROUND

Pelvic lymphadenectomy provides prognostic information for those diagnosed with endometrial (womb) cancer and provides information that may influence decisions regarding adjuvant treatment. However, studies have not shown a therapeutic benefit, and lymphadenectomy causes significant morbidity. The technique of sentinel lymph node biopsy (SLNB), allows the first draining node from a cancer to be identified and examined histologically for involvement with cancer cells. SLNB is commonly used in other cancers, including breast and vulval cancer. Different tracers, including colloid labelled with radioactive technetium-99, blue dyes, e.g. patent or methylene blue, and near infra-red fluorescent dyes, e.g. indocyanine green (ICG), have been used singly or in combination for detection of sentinel lymph nodes (SLN).

OBJECTIVES

To assess the diagnostic accuracy of sentinel lymph node biopsy (SLNB) in the identification of pelvic lymph node involvement in women with endometrial cancer, presumed to be at an early stage prior to surgery, including consideration of the detection rate.

SEARCH METHODS

We searched MEDLINE (1946 to July 2019), Embase (1974 to July 2019) and the relevant Cochrane trial registers.

SELECTION CRITERIA

We included studies that evaluated the diagnostic accuracy of tracers for SLN assessment (involving the identification of a SLN plus histological examination) against a reference standard of histological examination of removed pelvic +/- para-aortic lymph nodes following systematic pelvic +/- para-aortic lymphadenectomy (PLND/PPALND) in women with endometrial cancer, where there were sufficient data for the construction of two-by-two tables.

DATA COLLECTION AND ANALYSIS

Two review authors (a combination of HN, JM, NW, RG, and WH) independently screened titles and abstracts for relevance, classified studies for inclusion/exclusion and extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We calculated the detection rate as the arithmetic mean of the total number of SLNs detected out of the total number of women included in the included studies with the woman as the unit of analysis, used univariate meta-analytical methods to estimate pooled sensitivity estimates, and summarised the results using GRADE.

MAIN RESULTS

The search revealed 6259 unique records after removal of duplicates. After screening 232 studies in full text, we found 73 potentially includable records (for 52 studies), although we were only able to extract 2x2 table data for 33 studies, including 2237 women (46 records) for inclusion in the review, despite writing to trial authors for additional information. We found 11 studies that analysed results for blue dye alone, four studies for technetium-99m alone, 12 studies that used a combination of blue dye and technetium-99m, nine studies that used indocyanine green (ICG) and near infra-red immunofluorescence, and one study that used a combination of ICG and technetium-99m. Overall, the methodological reporting in most of the studies was poor, which resulted in a very large proportion of 'unclear risk of bias' ratings. Overall, the mean SLN detection rate was 86.9% (95% CI 82.9% to 90.8%; 2237 women; 33 studies; moderate-certainty evidence). In studies that reported bilateral detection the mean rate was 65.4% (95% CI 57.8% to 73.0%) . When considered according to which tracer was used, the SLN detection rate ranged from 77.8% (95% CI 70.0% to 85.6%) for blue dye alone (559 women; 11 studies; low-certainty evidence) to 100% for ICG and technetium-99m (32 women; 1 study; very low-certainty evidence). The rates of positive lymph nodes ranged from 5.2% to 34.4% with a mean of 20.1% (95% CI 17.7% to 22.3%). The pooled sensitivity of SLNB was 91.8% (95% CI 86.5% to 95.1%; total 2237 women, of whom 409 had SLN involvement; moderate-certainty evidence). The sensitivity for of SLNB for the different tracers were: blue dye alone 95.2% (95% CI 77.2% to 99.2%; 559 women; 11 studies; low-certainty evidence); Technetium-99m alone 90.5% (95% CI 67.7% to 97.7%; 257 women; 4 studies; low-certainty evidence); technetium-99m and blue dye 91.9% (95% CI 74.4% to 97.8%; 548 women; 12 studies; low-certainty evidence); ICG alone 92.5% (95% CI 81.8% to 97.1%; 953 women; 9 studies; moderate-certainty evidence); ICG and blue dye 90.5% (95% CI 63.2.6% to 98.1%; 215 women; 2 studies; low-certainty evidence); and ICG and technetium-99m 100% (95% CI 63% to 100%; 32 women; 1 study; very low-certainty evidence). Meta-regression analyses found that the sensitivities did not differ between the different tracers used, between studies with a majority of women with FIGO stage 1A versus 1B or above; between studies assessing the pelvic lymph node basin alone versus the pelvic and para-aortic lymph node basin; or between studies that used subserosal alone versus subserosal and cervical injection. It should be noted that a false-positive result cannot occur, as the histological examination of the SLN is unchanged by the results from any additional nodes removed at systematic lymphadenectomy.

AUTHORS' CONCLUSIONS

The diagnostic test accuracy for SLNB using either ICG alone or a combination of a dye (blue or ICG) and technetium-99m is probably good, with high sensitivity, where a SLN could be detected. Detection rates with ICG or a combination of dye (ICG or blue) and technetium-99m may be higher. The value of a SLNB approach in a treatment pathway, over adjuvant treatment decisions based on uterine factors and molecular profiling, requires examination in a high-quality intervention study.

Sentinel lymph node detection in endometrial cancer with indocyanine green: laparoscopic versus robotic approach

BACKGROUND

The aims of the present study were to assess bilateral sentinel lymph node (SLN) mapping with laparoscopic versus robotic approach, to assess variables affecting bilateral detection rates and to assess survival difference in patients with no/unilateral, compared to bilateral SLN detection.

METHODS

This is a retrospective, single-centre, observational cohort study, including patients with endometrial cancer FIGO stage IA-IVB, treated with minimally invasive primary surgery and undergoing indocyanine green (ICG) injection to detect SLN, between January 2015 and December 2019.

RESULTS

Of the 549 included patients, 286 (52.1%) and 263 (47.9%) underwent the laparoscopic and robotic approach respectively. 387 (70.5%) patients had bilateral SLN mapping, 102 (18.6%) and 60 (10.9%) had unilateral and no mapping, respectively. Patients who underwent the robotic approach were older (median 61 versus 64 years, p=0.046) and had a higher BMI (median 26.0 versus 34.8 kg/m2, p<0.001). No difference in any SLN mapping or in SLN bilateral detection was evident between the laparoscopic or robotic approach (p=0.892 and p=0.507 respectively). Patients with bilateral SLN detection in the entire cohort were younger (p<0.001) and had a better 3-year disease-free survival (DFS) compared to patients with no/unilateral SLN mapping (77.0% versus 66.3%, respectively, p=0.036). No 3-year overall survival (OS) difference was reported (p=0.491).

CONCLUSION

SLN mapping and bilateral SLN detection with ICG in endometrial cancer was not different in the laparoscopic and robotic approach, even though patients undergoing the robotic approach were older and more obese. Bilateral SLN detection was associated with improved 3-year DFS, but not with 3-year OS, compared to no and unilateral SLN detection.

Anatomic Asymmetry in Sentinel Lymph Node Detection in Endometrial Cancer

STUDY OBJECTIVE

To determine whether the concomitant use of indocyanine green (ICG) with technetium-99m-filtered sulfur colloid (Tc99m-FSC) improves bilateral sentinel lymph node (SLN) detection rate in endometrial cancer and whether anatomic concordance of pelvic lymph nodes exists and can be used to predict SLN location in cases of unilateral mapping failure.

DESIGN

Retrospective cohort study.

SETTING

Tertiary academic medical center in Holon, Israel.

PATIENTS

Patients diagnosed with endometrial cancer, who underwent SLN mapping with Tc99m-FSC, ICG, or both, at our center between 2014 and 2019.

INTERVENTIONS

A total of 111 patients were included in the study. SLN mapping using Tc99m-FSC was performed in 101 (91.9%) patients, and ICG injection was given to 64 (57.6%) patients of whom 55 (49.5%) received both. We compared SLN detection rates (unilateral and bilateral) and anatomic symmetry for each method alone and for a combination of the 2.

MEASUREMENTS AND MAIN RESULTS

The overall detection rate for unilateral SLNs was 96.4%; 96.9% with ICG, 93.1% with gamma-probe, and 98.2% by combining both methods. The total bilateral detection rate was 72.1%, with ICG performing better as a single tracer than Tc99m-FSC (75% vs 63.4%, respectively). In 55 women in whom both tracers were used, the bilateral detection rate was significantly higher compared with Tc99m-FSC alone. Symmetric pelvic anatomic concordance of SLN was found in only 35 of 80 patients with bilateral SLN detection (43.8%).

CONCLUSION

The combination of preoperative radioisotope injection and intraoperative ICG administration may yield the best bilateral SLN detection rate. In cases of unilateral mapping failure, one cannot rely on the anatomic location of the ipsilateral SLN detected to harvest the complementary node because the symmetric concordance is poor.