Sentinel lymph node mapping in early-stage cervical cancer: Meta-analysis

Comparative study using indocyanine green and patent blue dye for sentinel lymph node biopsy in patients with early-stage cervical cancer

BACKGROUND

Lymphatic involvement is the most important prognostic factor in early-stage cervical cancer. Sentinel lymph node biopsy is a viable alternative to systematic lymphadenectomy and may identify metastases more precisely.

OBJECTIVE

To compare two tracers (indocyanine green and patent blue) to detect sentinel nodes.

METHODS

A single-center, retrospective study of women treated due to early-stage cervical cancer (International Federation of Gynecology and Obstetrics 2009 IA1 with lymphovascular invasion, IA2, and IB1). Location and tracer of all detected sentinel nodes had been documented for a prospective, multicenter trial (SENTIX trial). All sentinel nodes were sent to frozen section and final analysis through ultrastaging using a standard protocol.

RESULTS

Overall, 103 patients were included. Bilateral detection rate for indocyanine green (93.2%) was significantly higher than for blue dye (77.7%; p=0.004). Their combined use significantly increased the bilateral detection to 99.0% (p=0.031). While 97.4% of all sentinel nodes were located below the common iliac vessels, no para-aortic nodes were labeled. Simultaneous bilateral detection with both tracers was found in 71.8% of the cases, of which the sentinel nodes were identical in 91.9%. Nine positive nodes were detected among seven patients (6.8%), all marked with indocyanine green while patent blue labeled six. Frozen section failed to detect one of three macrometastases and three of four micrometastases (sensitivity 43%; negative prediction value 96%).

CONCLUSION

Anatomical distribution and topographic localization of the sentinel nodes obtained with these tracers were not different. Indocyanine green provided a significantly higher bilateral detection rate and had superior sensitivity to detect positive nodes compared with patent blue. Combining indocyanine green and blue dye increased the bilateral detection rate significantly.

Nuclear Medicine and Molecular Imaging Applications in Gynecologic Malignancies: A Comprehensive Review

Gynecologic malignancies, consisting of endometrial, cervical, ovarian, vulvar, and vaginal cancers, pose significant diagnostic and management challenges due to their complex anatomic location and potential for rapid progression. These tumors cause substantial morbidity and mortality, often because of their delayed diagnosis and treatment. An estimated 19% of newly diagnosed cancers among women are gynecologic in origin. In recent years, there has been growing evidence supporting the integration of nuclear medicine imaging modalities in the diagnostic work-up and management of gynecologic cancers. The sensitivity of fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET) combined with the anatomical specificity of computed tomography (CT) and magnetic resonance imaging (MRI) allows for the hybrid evaluation of metabolic activity and structural abnormalities that has become an indispensable tool in oncologic imaging. Lymphoscintigraphy, using technetium 99m (99mTc) based radiotracers along with single photon emission computed tomography/ computed tomography (SPECT/CT), holds a vital role in the identification of sentinel lymph nodes to minimize the surgical morbidity from extensive lymph node dissections. While not yet standard for gynecologic malignancies, promising therapeutic nuclear medicine agents serve as specialized treatment options for patients with advanced or recurrent disease. This article aims to provide a comprehensive review on the nuclear medicine applications in gynecologic malignancies through the following objectives: 1) To describe the role of nuclear medicine in the initial staging, lymph node mapping, response assessment, and recurrence/surveillance imaging of common gynecologic cancers, 2) To review the limitations of 18F-FDG PET/CT and promising applications of 18F-FDG PET/MRI in gynecologic malignancy, 3) To underscore the promising theragnostic applications of nuclear medicine, 4) To highlight the current role of nuclear medicine imaging in gynecologic cancers as per the National Comprehensive Cancer Network (NCCN), European Society of Surgical Oncology (ESGO), and European Society of Medical Oncology (ESMO) guidelines.

Current applications of indocyanine green (ICG) in abdominal, gynecologic and urologic surgery: a meta-review and quality analysis with use of the AMSTAR 2 instrument

BACKGROUND

Indocyanine green (ICG) is an injectable fluorochrome that has recently gained popularity as a means of assisting intraoperative visualization during laparoscopic and robotic surgery. Many systematic reviews and meta-analyses have been published. We conducted a meta-review to synthesize the findings of these studies.

METHODS

PubMed and Embase were searched to identify systematic reviews and meta-analyses coping with the uses of ICG in abdominal operations, including Metabolic Bariatric Surgery, Cholecystectomy, Colorectal, Esophageal, Gastric, Hepato-Pancreato-Biliary, Obstetrics and Gynecology (OG), Pediatric Surgery, Surgical Oncology, Urology, (abdominal) Vascular Surgery, Adrenal and Splenic Surgery, and Interdisciplinary tasks, until September 2023. We submitted the retrieved meta-analyses to qualitative analysis based on the AMSTAR 2 instrument.

RESULTS

We identified 116 studies, 41 systematic reviews (SRs) and 75 meta-analyses (MAs), spanning 2013-2023. The most thoroughly investigated (sub)specialties were Colorectal (6 SRs, 25 MAs), OG (9 SRs, 15 MAs), and HPB (4 SRs, 12 MAs). Interestingly, there was high heterogeneity regarding the administered ICG doses, routes, and timing. The use of ICG offered a clear benefit regarding anastomotic leak prevention, particularly after colorectal and esophageal surgery. There was no clear benefit regarding sentinel node detection after OG. According to the AMSTAR 2 tool, most meta-analyses ranked as "critically low" (34.7%) or "low" (58.7%) quality. There were only five meta-analyses (6.7%) that qualified as "moderate" quality, whereas there were no "high" quality reviews.

CONCLUSIONS

Regardless of the abundance of pertinent literature and reviews, surgeons should be cautious when interpreting their results on ICG use in abdominal surgery. Future reviews should focus on ensuring methodological vigor; establishing clear protocols of ICG dose, route of administration, and timing; and improving reporting quality. Other sources of data (e.g., registries) and novel methods of data analysis (e.g., machine learning) might also contribute to an enhanced role of ICG as a decision-making tool in surgery.

Development of novel tracers for sentinel node identification in cervical cancer

Indocyanine green (ICG) with near-infrared (NIR) fluorescence imaging is used for lymphatic mapping. However, binding of ICG to blood proteins like serum albumin can shorten its retention time in sentinel lymph nodes (SLNs). Here, we investigated the efficacy and safety of a new fluorescence tracer comprising phytate and liposome (LP)-encapsulated ICG. Coadministration of phytate with LP containing phosphatidic acid promotes chelation mediated by Ca2+ in bodily fluids to enhance SLN retention. Uniformly sized LPs (100 nm) encapsulating ICG under conditions that minimized fluorescence self-quenching during storage were produced. We analyzed the behavior of the new tracer (ICG-phytate-LP) and control tracers (ICG and ICG-LP) in the lymphatic flow of mice in terms of lymph node retention time. We also tested lymphatic flow and safety in pigs that have a more human-like lymphatic system. LPs encapsulating stabilized ICG were successfully prepared. Mixing LP with phytate in the presence of Ca2+ increased both the particle size and negative surface charge. In mice, ICG-phytate-LP had the best lymph node retention, with a fluorescence intensity ratio that increased over 6 h and then decreased slowly over the next 24 h. In pigs, administration of ICG and ICG-phytate-LP resulted in no death or weight loss. There were no obvious differences between blood test results for the ICG and ICG-phytate-LP groups, and the overall safety was good. ICG-phytate-LP may be a useful new tracer for gynecological cancers that require time for lymph node identification due to a retroperitoneal approach.

Feasibility of Sentinel Lymph Node Biopsy in Early-Stage Epithelial Ovarian Cancer: A Systematic Review and Meta-Analysis

Sentinel lymph node biopsy (SLNB) has been widely adopted in the management of early-stage gynaecological cancers such as endometrial, vulvar and cervical cancer. Comprehensive surgical staging is crucial for patients with early-stage ovarian cancer and currently, that includes bilateral pelvic and para-aortic lymph node assessment. SLNB allows the identification, excision and pathological assessment of the first draining lymph nodes, thus negating the need for a full lymphadenectomy. We systematically searched the MEDLINE, Embase and Cochrane Central Register of Controlled Trials (CENTRAL) databases (from inception to 3 November 2022) in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Our search identified 153 articles from which 11 were eligible for inclusion. Patients with clinical stage I-II ovarian cancer undergoing sentinel lymph node biopsy were included. Statistical analysis was performed in RStudio using the meta package, where meta-analysis was performed for the detection. The risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies C (QUADAS-C) tool. Overall, 11 observational studies met the predetermined criteria and these included 194 women. The meta-analysis showed that the detection rate of sentinel lymph nodes in early-stage ovarian cancer was 94% (95% CI of 86% to 1.00%). Significant heterogeneity was noted among the studies with Q = 47.6, p < 0.0001, I2 = 79% and τ2 = 0.02. Sentinel lymph nodes in early-stage ovarian cancer have a high detection rate and can potentially have applicability in clinical practice. However, considering the small number of participants in the studies, the heterogeneity among them and the low quality of evidence, the results should be interpreted with caution. Larger trials are needed before a change in clinical practice is recommended.

Predictors of Non-Sentinel Lymph Node Metastasis in Patients with Positive Sentinel Lymph Node in Early-Stage Cervical Cancer: A SENTICOL GROUP Study

BACKGROUND

The goal of this study was to identify the risk factors for metastasis in the remaining non-sentinel lymph nodes (SLN) in the case of positive SLN in early-stage cervical cancer.

METHODS

An ancillary analysis of two prospective multicentric databases on SLN biopsy for cervical cancer (SENTICOL I and II) was performed. Patients with early-stage cervical cancer (FIGO 2018 IA to IIA1), with bilateral SLN detection and at least one positive SLN after ultrastaging, were included.

RESULTS

405 patients were included in SENTICOL I and Il. Fifty-two patients had bilateral SLN detection and were found to have SLN metastasis. After pelvic lymphadenectomy, metastatic involvement of non-SLN was diagnosed in 7 patients (13.5%). Patients with metastatic non-SLN were older (51.9 vs. 40.8 years, p = 0.01), had more often lympho-vascular space invasion (LVSI) (85.7% vs. 35.6%, p = 0.03), and had more often parametrial involvement (42.9% vs. 6.7%, p = 0.003). Multivariate analysis retained age (OR = 1.16, 95% IC = [1.01-1.32], p = 0.03) and LVSI (OR = 25.97, 95% IC = [1.16-582.1], p = 0.04) as independently associated with non-SLN involvement.

CONCLUSIONS

Age and LVSI seemed to be predictive of non-SLN metastasis in patients with SLN metastasis in early-stage cervical cancer. Larger cohorts are needed to confirm the results and clinical usefulness of such findings.

Finding the sentinel lymph node in early cervical cancer: When is unusual not uncommon?

OBJECTIVE

To report our institutional experience with sentinel lymph node (SLN) detection using indocyanine green for cervical cancer, in terms of detection rates, detection of SLN at unusual locations, and factors associated with unusual SLN locations. In addition, we performed a systematic review of the literature to identify factors associated with unusual SLN localizations.

METHODS

This is a retrospective cohort study of women with early-stage cervical cancer undergoing sentinel lymph node mapping between 2015 and 2019. Outcome measures were SLN detection rates, detection rates of unusual locations for SLN and risk factors for aberrant lymphatic drainage pathways. In addition, studies evaluating factors associated with unusual SLN locations in cervical cancer were assessed in a systematic review.

RESULTS

A total of 100 patients were included. The unilateral SLN detection rate was 88%, whereas the bilateral detection rate was 75%. In 37% of all patients, SLN were found in unusual locations, and in 10% of patients SLN were solely found in unusual locations. Body mass index (BMI) was associated with finding SLN in unusual locations, with unusual nodes detected in 52% of patients with BMI <25 kg/m² and in 28% of patients with BMI ≥25 kg/m². The systematic review identified three studies, identifying lower BMI, nulliparity and tumor size of >20 mm as factors associated with finding SLN at unusual locations.

CONCLUSION

Aberrant drainage sites represent a significant proportion of SLN detected in cervical cancer. Factors associated with increased rates of unusual nodal locations are a lower BMI, with a possible association with nulliparity and tumor size of >20 mm.

The Oncological Implication of Sentinel Lymph Node in Early Cervical Cancer: A Meta-Analysis of Oncological Outcomes and Type of Recurrences

Background and Objectives: Pelvic lymphadenectomy has been associated with radical hysterectomy for the treatment of early Cervical Cancer (ECC) since 1905. However, some complications are related to this technique, such as lymphedema and nerve damage. In addition, its clinical role is controversial. For this reason, the sentinel lymph node (SLN) has found increasing use in clinical practice over time. Oncologic safety, however, is debated, and there is no clear evidence in the literature regarding this. Therefore, our meta-analysis aims to schematically analyze the current scientific evidence to investigate the non-inferiority of SLN versus PLND regarding oncologic outcomes. Materials and Methods: Following the recommendations in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, we systematically searched the PubMed and Scopus databases in June 2022 since their early first publications. We made no restrictions on the country. We considered only studies entirely published in English. We included studies containing Disease-Free Survival (DFS), Overall Survival (OS), Recurrence Rate (RR), and site of recurrence data. We used comparative studies for meta-analysis. We registered this meta-analysis to the PROSPERO site for meta-analysis with protocol number CRD42022316650. Results: Twelve studies fulfilled inclusion criteria. The four comparative studies were enrolled in meta-analysis. Patients were analyzed concerning Sentinel Lymph Node Biopsy (SLN) and compared with Bilateral Pelvic Systematic Lymphadenectomy (PLND) in early-stage Cervical Cancer (ECC). Meta-analysis highlighted no differences in oncological safety between these two techniques, both in DFS and OS. Moreover, most of the sites of recurrences in the SLN group seemed not to be correlated with missed lymphadenectomy. Conclusions: Data in the literature do not seem to show clear oncologic inferiority of SLN over PLND. On the contrary, the higher detection rate of positive lymph nodes and the predominance of no lymph node recurrences give hope that this technique may equal PLND in oncologic terms, improving its morbidity profile.

Prognostic Value of Lymph Node Characteristics in Patients with Cervical Cancer Treated with Radical Hysterectomy

Objective

This study evaluated the prognostic value of various lymph node (LN) characteristics, including the lymph node ratio (LNR), in patients with cervical cancer treated with radical hysterectomy.

Methods

In this retrospective study, 260 patients with cervical cancer who had undergone radical hysterectomy with pelvic or paraaortic lymphadenectomies were included. LN characteristics related to several LN statuses included total LN counts, LN metastasis, total positive LN counts, LNR, and levels of lymphadenectomy. LNR was defined as the number of metastatic LNs divided by the total number of LNs harvested. Univariate and multivariate analyses for disease-free survival (DFS) and overall survival (OS) were performed using the clinicopathological and LN characteristics.

Results

Based on receiver-operating characteristics curve analysis, the cut-off value of LNR was 0.0625. Multivariate analysis revealed that high LNR was significantly related to tumor recurrence (hazard ratio [HR], 5.182; 95% confidence interval [CI], 2.424–11.075; p < 0.0001). After adjusting for clinicopathological factors, LNR was also independent prognostic factor for predicting tumor recurrence (HR, 5.930; 95% CI, 2.114–16.634; p = 0.0007). However, total retrieved LN counts and level of lymphadenectomy were not associated with survival outcomes.

Conclusion

LNR may be a prognostic biomarker for predicting disease recurrence in cervical cancer treated with radical hysterectomy.