Immunohistochemical workup of sentinel nodes in endometrial cancer improves diagnostic accuracy

Establishing guidelines for sentinel lymph node ultrastaging in endometrial cancer

BACKGROUND

Many sentinel lymph node (SLN) ultrastaging protocols for endometrial cancer exist, but there is no consensus method.

OBJECTIVE

This study aims to develop guidelines for size criteria in SLN evaluation for endometrial cancer, to determine whether a single cytokeratin AE1:AE3 immunohistochemical slide provides sufficient data for diagnosis, and to compare cost efficiency between current and limited ultrastaging protocols at a large tertiary care institution.

METHODS

Our current SLN ultrastaging protocol consists of cutting two adjacent paraffin block sections at two levels (L1 and L2), 50 μm apart, with two slides at each level stained with hematoxylin and eosin and cytokeratin AE1:AE3 immunohistochemistry. We retrospectively reviewed digitized L1 and L2 slides of all positive ultrastaged SLNs from patients treated for endometrial cancer between January 2013 and January 2020. SLN diagnosis was defined by measuring the largest cluster of contiguous tumor cells in a single cross section: macrometastasis (>2.0 mm), micrometastasis (>0.2 to ≤2.0 mm or >200 cells), or isolated tumor cells (≤0.2 mm or ≤200 cells). Concordance between L1 and L2 results was evaluated. Cost efficiency between current (two immunohistochemical slides per block) and proposed limited (one immunohistochemical slide per block) protocols was compared.

RESULTS

Digitized slides of 147 positive SLNs from 109 patients were reviewed; 4.1% of SLNs were reclassified based on refined size criteria. Complete concordance between L1 and L2 interpretations was seen in 91.8% of SLNs. A false-negative rate of 0%-0.9% in detecting micrometastasis and macrometastasis using a limited protocol was observed. Estimated charge-level savings of a limited protocol were 50% per patient.

CONCLUSION

High diagnostic accuracy in SLN interpretation may be achieved using a limited ultrastaging protocol of one immunohistochemical slide per block and linear measurement of the largest cluster of contiguous tumor cells. Implementation of the proposed limited ultrastaging protocol may result in laboratory cost savings with minimal impact on health outcomes.

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.

Ultrastaging methods of sentinel lymph nodes in endometrial cancer - a systematic review

OBJECTIVE

Sentinel lymph node mapping has emerged as an alternative to lymphadenectomy in evaluating the lymph node status in endometrial cancer. Several pathological methods to examine the sentinel lymph node are applied internationally. The aim of this study was to determine the value of ultrastaging and to assess the ultrastaging method with the highest detection rate of metastases.

METHODS

A systematic review was conducted. Inclusion criteria were: pathologically-confirmed endometrial cancer with sentinel lymph node mapping, report of the histological outcomes, metastases found by hematoxylin and eosin staining and metastases found by ultrastaging were separately mentioned, and description of the ultrastaging method. The primary outcome was the detection of metastases found by ultrastaging that were not detected by routine hematoxylin and eosin staining. The secondary outcome was the difference in detection rate of metastases between several ultrastaging methods. Random effects meta-analyses were conducted.

RESULTS

Fifteen studies were selected, including 2259 patients. Sentinel lymph nodes were examined by routine hematoxylin and eosin staining. Subsequently, multiple ultrastaging methods were used, with differences in macroscopic slicing (bread-loaf/longitudinal), number of microscopic slides, and distance between slides, but all used immunohistochemistry. A positive sentinel lymph node was found in 14% of patients. In 37% of these, this was detected only by ultrastaging. Using more ultrastaging slides did not result in a higher detection rate. Bread-loaf slicing led to a higher detection rate compared with longitudinal slicing (mean detection rates 53% and 33%, respectively).

CONCLUSION

Pathological ultrastaging after routine hematoxylin and eosin staining in endometrial cancer patients has led to an increased detection rate of sentinel lymph node metastases. Different ultrastaging methods are used, with a preference for bread-loaf slicing. However, due to the large heterogeneity of the studies, assessing which ultrastaging method has the highest detection rate of sentinel lymph node metastases was not possible.

The role of sentinel lymph node mapping in endometrial carcinoma

Endometrial cancer is the most commonly diagnosed gynecological malignancy in developing countries, and the second malignancy after cervical cancer in developing countries. The primary treatment is based on surgical and pathologic staging including extrafascial type A radical hysterectomy bilateral salpingo-oophorectomy and pelvic and latero-aortic lymphadenectomy. Minimally invasive surgery is the most widely used technique. Sentinel node biopsy is part of this concept and has reached the management of endometrial cancer. The aim of this review was to describe the history, the different injection techniques and results of sentinel node biopsy, and analyze the future role of this technique in endometrial carcinoma.

One-Step Nucleic Acid Amplification (OSNA): A fast molecular test based on CK19 mRNA concentration for assessment of lymph-nodes metastases in early stage endometrial cancer

INTRODUCTION

The aim of the current study is to evaluate the detection rate of micro- and macro-metastases of the One-Step Nucleic Acid Amplification (OSNA) compared to frozen section examination and subsequent ultra-staging examination in early stage endometrial cancer (EC).

MATERIAL AND METHODS

From March 2016 to June 2016, data of 40 consecutive FIGO stage I EC patients were prospectively collected in an electronic database. The sentinel lymph node mapping was performed in all patients. All mapped nodes were removed and processed. Sentinel lymph nodes were sectioned and alternate sections were respectively examined by OSNA and by frozen section analysis. After frozen section, the residual tissue from each block was processed with step-level sections (each step at 200 micron) including H&E and IHC slides.

RESULTS

Sentinel lymph nodes mapping was successful in 29 patients (72.5%). In the remaining 11 patients (27.5%), a systematic pelvic lymphadenectomy was performed. OSNA assay sensitivity and specificity were 87.5% and 100% respectively. Positive and negative predictive values were 100% and 99% respectively, with a diagnostic accuracy of 99%. As far as frozen section examination and subsequent ultra-staging analysis was concerned, we reported sensitivity and specificity of 50% and 94.4% respectively; positive and negative predictive values were 14.3% and 99%, respectively, with an accuracy of 93.6%. In one patient, despite negative OSNA and frozen section analysis of the sentinel node, a macro-metastasis in 1 non-sentinel node was found.

CONCLUSIONS

The combination of OSNA procedure with the sentinel lymph node mapping could represent an efficient intra-operative tool for the selection of early-stage EC patients to be submitted to systematic lymphadenectomy.

Sentinel lymph node procedure in endometrial cancer: A systematic review and proposal for standardization of future research

OBJECTIVES

Sentinel lymph node (SLN) procedure could be an attractive solution to the debate on lymphadenectomy in endometrial cancer; however challenges to interpreting the literature include marked heterogeneity across studies, a wide variety of injection techniques and a lack of uniformly accepted definitions for important outcomes. We aim to critically appraise the published literature and streamline terminology and methodology for future studies in this field.

METHODS

We conducted a PubMed search and included all original research of endometrial cancer patients having undergone SLN procedure with an n>30. Data collected included injection technique, unilateral, bilateral, and para-aortic detection rates, and ultrastaging results. When different definitions were used for reporting outcomes, we recalculated the original study results according to our proposed definitions. Data was analyzed using descriptive statistics.

RESULTS

Seventeen studies met our inclusion criteria. Injection sites were categorized into cervical versus corporeal. Overall detection rates ranged from 60 to 100%; studies with n>100 all had overall detection rates of >80%. Bilateral detection rates were higher with a combination of two injection agents. Para-aortic mapping was most frequent after corporeal injection techniques (39%), and was higher after deep vs. standard cervical injection (17% vs. 2%). The proportion of metastatic lymph nodes diagnosed through ultrastaging was high (around 40%) and ultrastaging of SLN upstaged approximately 5% of patients. Retrospectively applying a surgical algorithm revealed a sensitivity of 95%, a negative predictive value of 99%, and a false negative rate of 5% (with only 9 false negative cases remaining in total).

CONCLUSION

Results of SLN research for endometrial cancer are promising. We believe that in future studies, uniform reporting is needed to improve our understanding of the safety and feasibility of SLN in EC. We propose 2 strategies: a checklist of elements to include in future reports and the standardization of key definitions.

A new diagnostic method for rapid detection of lymph node metastases using a one-step nucleic acid amplification (OSNA) assay in endometrial cancer

BACKGROUND

To improve lymph node (LN) metastasis identification for patients with endometrial cancer (EC), this study assessed the usefulness of molecular biologic techniques using a one-step nucleic acid amplification (OSNA) assay.

METHODS

Using quantitative reverse transcription polymerase chain reaction (qRT-PCR), an optimal mRNA marker was selected, and its expression was compared between histopathologically positive and negative LNs using an OSNA assay. The authors determined copy number cutoff values and evaluated the diagnostic performance of this OSNA assay using sentinel lymph nodes (SLNs). They also investigated whether an OSNA assay could detect LN metastases with sensitivity and specificity equivalent to the 2-mm-interval histopathology method.

RESULTS

For analysis of EC samples, cytokeratin 19 (CK19) was selected as a useful mRNA marker for the OSNA assay. When the cutoff value was set at 250 copies (using 215 LNs from 70 patients), an OSNA assay using CK19 mRNA had a sensitivity of 93.3%, a specificity of 99.5%, and a concordance rate of 99.1%. For performance evaluations using SLNs (120 histopathologically negative LNs and 17 histopathologically positive LNs from 35 patients), a OSNA assay using CK19 mRNA had a sensitivity of 82.4%, a specificity of 99.2%, a positive predictive value of 93.3%, and a concordance rate of 97.1%. Thus, an OSNA assay using CK19 mRNA provided results equivalent to those with the 2-mm-interval histopathology method.

CONCLUSIONS

The study data demonstrated that an OSNA assay using CK19 mRNA was applicable for detecting LN metastases in EC. Combined analysis using an OSNA assay and SLNs may improve individualized treatments according to LN metastatic status.

Histological features associated with occult lymph node metastasis in FIGO clinical stage I, grade I endometrioid carcinoma

AIMS

Lymph node involvement affects prognosis/treatment in endometrial carcinoma patients. We assessed various histological features associated with nodal metastasis in patients with grade I, stage I endometrial endometrioid carcinoma (EEC).

METHODS AND RESULTS

Eighteen stage I EECs with occult positive lymph nodes and 36 controls were assessed for depth of myoinvasion; microcystic, elongated and fragmented (MELF) pattern of myometrial invasion; lymphovascular invasion (LVI); and epithelial metaplasia. Nodal metastases were subclassified as isolated tumour cells (ITCs; ≤0.2 mm), micrometastasis (>0.2 mm and <2 mm), or macrometastasis (≥2 mm). Node-positive cases had significantly higher rates of LVI (P < 0.001) and MELF invasion (P = 0.003) on univariate analysis. Only LVI was associated significantly with nodal metastasis on multivariate analysis (P = 0.002). Tumours with MELF invasion demonstrated reduced E-cadherin expression. Macrometastases were identified in seven cases (39%) with or without micrometastasis/ITCs. Eight (44%) contained only ITCs. Eleven (61%) had histiocyte-like nodal metastases. Biopsy material from four of six (67%) and five of 17 (29%) cases with and without nodal metastasis showed detached eosinophilic tumour cell buds. Of the former, three were associated with histiocyte-like nodal metastases - a feature absent in biopsies without tumour budding.

CONCLUSIONS

Lymph nodes from grade I EEC exhibiting cellular budding or LVI should be examined for occult metastases, especially in the form of histiocyte-like cells.

Contribution of pelvic and para-aortic lymphadenectomy with sentinel node biopsy in patients with IB2-IIB cervical cancer

Objective:

Detection of lymph node involvement in women with IB2–IIB cervical cancer could have a positive effect on survival. We set out to evaluate the incidence of pelvic and/or para-aortic lymph node involvement using the sentinel node (SN) biopsy and its impact on survival.

Methods:

From 2002 to 2010, 66 women with IB2–IIB cervical cancer underwent a pelvic and paraaortic lymphadenectomy with SN biopsy. Survival between groups according to lymph node status was evaluated.

Results:

Mean tumour size was 43.5 mm. At least one SN was detected in 69% of the 45 SN procedures performed. Sixteen of these patients had metastatic SN and the false negative rate was 20%. Metastatic pelvic SNs or non-SNs were detected in 33 patients (50%), including pelvic-positive nodes in 26 (40%), pelvic- and paraaortic-positive lymph nodes in seven (11%), and paraaortic skip metastases in two (6%). Positive paraaortic node was the sole determinant for disease-free survival (DFS) and overall survival (OS; P<0.001). Differences in DFS and OS between groups according to the nodal status were observed (P<0.001).

Conclusion:

SN procedure gave a higher rate of metastasis detection. Further studies are required to evaluate whether pre-therapeutic node staging, including paraaortic and pelvic lymphanedectomy, should be performed.

Sentinel lymph node biopsy in endometrial cancer: meta-analysis of 26 studies

OBJECTIVE

The validity of the sentinel lymph node (SLN) procedure for the assessment of nodal status in patients with endometrial cancer is unclear. We aimed to assess the diagnostic performance of this procedure.

METHODS

We searched the PubMed and Embase databases for studies published before June 1, 2011. Eligible studies had a sample size of at least 10 patients, and reported the detection rate and/or sensitivity of the SLN biopsy.

RESULTS

We identified 26 eligible studies, which included 1101 SLN procedures. The overall weighted-mean number of harvested SLNs was 2.6. The detection rate and the sensitivity were 78% (95% confidence interval [CI]=73%-84%) and 93% (95% CI=87%-100%), respectively. Significant between-study heterogeneity was observed in the analysis of the detection rate (I-squared statistic, 80%). The use of pericervical injection was correlated with the increase of the detection rate (P=0.031). The hysteroscopic injection technique was associated with the decrease of the detection rate (P=0.045) and the subserosal injection technique was associated with the decrease of the sensitivity (P=0.049), if they were not combined with other injection techniques. For the detection rate, significant small-study effects were noted (P<0.001).

CONCLUSIONS

Although SLN biopsy has shown good diagnostic performance in endometrial cancer, such performance should be interpreted with caution because of significant small study effects. Current evidence is not yet sufficient to establish the true performance of SLN biopsy in endometrial cancer.

Does the use of the 2009 FIGO classification of endometrial cancer impact on indications of the sentinel node biopsy?

Background

Lymphadenectomy is debated in early stages endometrial cancer. Moreover, a new FIGO classification of endometrial cancer, merging stages IA and IB has been recently published. Therefore, the aims of the present study was to evaluate the relevance of the sentinel node (SN) procedure in women with endometrial cancer and to discuss whether the use of the 2009 FIGO classification could modify the indications for SN procedure.

Methods

Eighty-five patients with endometrial cancer underwent the SN procedure followed by pelvic lymphadenectomy. SNs were detected with a dual or single labelling method in 74 and 11 cases, respectively. All SNs were analysed by both H&E staining and immunohistochemistry. Presumed stage before surgery was assessed for all patients based on MR imaging features using the 1988 FIGO classification and the 2009 FIGO classification.

Results

An SN was detected in 88.2% of cases (75/85 women). Among the fourteen patients with lymph node metastases one-half were detected by serial sectioning and immunohistochemical analysis. There were no false negative case. Using the 1988 FIGO classification and the 2009 FIGO classification, the correlation between preoperative MRI staging and final histology was moderate with Kappa = 0.24 and Kappa = 0.45, respectively. None of the patients with grade 1 endometrioid carcinoma on biopsy and IA 2009 FIGO stage on MR imaging exhibited positive SN. In patients with grade 2-3 endometrioid carcinoma and stage IA on MR imaging, the rate of positive SN reached 16.6% with an incidence of micrometastases of 50%.

Conclusions

The present study suggests that sentinel node biopsy is an adequate technique to evaluate lymph node status. The use of the 2009 FIGO classification increases the accuracy of MR imaging to stage patients with early stages of endometrial cancer and contributes to clarify the indication of SN biopsy according to tumour grade and histological type.