Histologic localization of sentinel lymph node metastases in breast cancer

A magnetic resonance imaging (MRI)-based nomogram for predicting lymph node metastasis in rectal cancer: a node-for-node comparative study of MRI and histopathology

BACKGROUND

The aim of the present study was to investigate the potential risk factors for lymph node metastasis (LNM) in rectal cancer using magnetic resonance imaging (MRI), and to construct and validate a nomogram to predict its occurrence with node-for-node histopathological validation.

METHODS

Our prediction model was developed between March 2015 and August 2016 using a prospective primary cohort (32 patients, mean age: 57.3 years) that included 324 lymph nodes (LNs) from MR images with node-for-node histopathological validation. We evaluated multiple MRI variables, and a multivariable logistic regression analysis was used to develop the predictive nomogram. The performance of the nomogram was assessed with respect to its calibration, discrimination, and clinical usefulness. The performance of the nomogram in predicting LNM was validated in an independent clinical validation cohort comprising 182 consecutive patients.

RESULTS

The predictors included in the individualized prediction nomogram were chemical shift effect (CSE), nodal border, short-axis diameter of nodes, and minimum distance to rectal cancer or rectal wall. The nomogram showed good discrimination (C-index: 0.947; 95% confidence interval: 0.920-0.974) and good calibration in the primary cohort. Decision curve analysis confirmed the clinical usefulness of the nomogram in predicting the status of each LN. For the prediction of LN status in the clinical validation cohort by readers 1 and 2, the areas under the curves using the nomogram were 0.890 and 0.841, and the areas under the curves of readers using their experience were 0.754 and 0.704, respectively. Diagnostic efficiency was significantly improved by using the nomogram (P<0.001).

CONCLUSIONS

The nomogram, which incorporates CSE, nodal location, short-axis diameter, and minimum distance to rectal cancer or rectal wall, can be conveniently applied in clinical practice to facilitate the prediction of LNM in patients with rectal cancer.

Sentinel lymph node metastases in cancer: causes, detection and their role in disease progression

Malignant tumors of ectodermal or endodermal origin may metastasize to the sentinel lymph node, the first lymph node encountered by tumor cells that enter lymphatics in the organ of origin. This pathway is enabled by the anatomy of the disease and the causes of metastasis are the result of complex interactions that include mechanical forces within the tumor and host tissues, and molecular factors initiated by tumor cell proliferation, elaboration of cytokines and changes in the tumor microenvironment. Mechanical stresses may influence complex biochemical, genetic and other molecular events and enhance the likelihood of metastasis. This paper summarizes our understanding of interacting molecular, anatomical and mechanical processes which facilitate metastasis to SLNs. Our understanding of these interacting events is based on a combination of clinical and basic science research, in vitro and in vivo, including studies in lymphatic embryology, anatomy, micro-anatomy, pathology, physiology, molecular biology and mechanobiology. The presence of metastatic tumor in the SLN is now more accurately identifiable and, based upon prospective clinical trials, paradigm-changing SLN biopsy has become the standard of clinical practice in breast cancer and melanoma.

Nano-imaging of the lymph network structure with quantum dots

Sentinel lymph node diagnosis contributes to operative strategy in cancer surgery. During lymph node metastasis, cancer cells first reach the sentinel lymph node (SLN) via lymph flow. To perform SLN biopsy effectively, it is important that cancer cells are detected with high sensitivity in SLN connected to the tumor site. Here we present a method to visualize a high-risk area in the SLN for lymph node metastasis with a high degree of accuracy. Quantum dots (QDs), bright fluorescent nanoparticles, were endoscopically injected into the gastrointestinal wall of pigs, and their signal was specifically detected in the SLN with a laparoscopic device. Single-particle imaging under a confocal microscope showed that the QDs were distributed heterogeneously in the SLN and that their distribution marked the inflow locus of afferent lymphatic vessels where lymph node metastasis begins. Moreover, we developed a method using cellular marker conjugated QDs that visualizes specific cells in SLNs, suggesting that this method can be applied for the detection of cancer cells in sentinel lymph nodes using tumor-specific-molecular conjugated QDs. These results show that our method might significantly increase the detection rate of cancer metastasis in SLNs.

Malignant cells are not found in ovarian cortex from breast cancer patients undergoing ovarian cortex cryopreservation

BACKGROUND

Breast cancer is a frequent indication for ovarian cortex cryopreservation due to its high incidence. The main concern of this procedure is the possibility of reintroducing metastatic cells within the implant, an issue that has not been addressed systematically. Thus, a study was designed to analyse the presence of ovarian metastases in breast cancer patients undergoing ovarian tissue cryopreservation.

METHODS

Morphological and immunohistochemical studies following the concept of the sentinel lymph node (SLN) were performed on 100 cortical ovarian biopsies obtained from 63 patients and on six frozen-thawed entire cortex from patients with the diagnosis of infiltrating ductal breast carcinoma undergoing ovarian cortex extraction and cryopreservation. The antibody panel included Cytokeratin CAM 5.2, Gross Cystic Disease Fluid Protein-15 (GCDFP15), Wilms' tumour antigen-1 (WT1) and Mammaglobin 1.

RESULTS

Employing only morphologic criteria, suspicious neoplastic cells were detected in five biopsies, but in none of the six entire cortex analysed. These five cases were reclassified as hyperplasic surface epithelium-inclusion cysts (CAM 5.2+, WT1+) or apoptotic granulosa cells (CAM 5.2-, GCDFP15+, WT1-).

CONCLUSIONS

Using the methodology of the SLN our data suggest the absence of tumour cells in biopsies obtained from patients undergoing ovarian cortex cryopreservation to preserve their fertility potential, although future methods of cancer screening may change our perception of this procedure.

Pathologic examination of sentinel lymph nodes from melanoma patients

In melanoma patients, the sentinel node biopsy (SNB) procedure is a highly accurate staging method, and the tumor-harboring status of the sentinel node (SN) is the most important prognostic factor for patients with early stage disease. For the SN to provide accurate prognostic information, however, it is essential that all "true" SNs are removed and examined diligently. Pathologists should examine multiple hematoxylin-eosin and immunohistochemically stained sections from each SN, but it is unclear from the currently available evidence what is the most appropriate sectioning and staining protocol. Relevant factors to consider include the accuracy of the procedure, the time, labor, and costs involved, and clinical follow-up data which are likely to vary between institutions; hence, individual protocols should be developed locally by pathologists in consultation with their surgical colleagues. At the Sydney Melanoma Unit, four sequential sections of both halves of each SN are examined. The first and fourth sections are stained with hematoxylin-eosin, the second section is stained for S-100 protein, and the third section is stained for HMB-45. Pathologists should not only identify the presence of melanoma metastases within the SN, but also record the size of the largest metastatic focus, tumor penetrative depth (measured from the inner margin of the node capsule to the deepest tumor cell within the SN), and the percentage nodal cross-sectional area involved (as measured on the slides). Potential diagnostic pitfalls in SN evaluation include the misinterpretation of nevus cells, macrophages, or antigen-presenting interdigitating dendritic cells as melanoma. Careful assessment of the morphologic characteristics of the cells and their immunohistochemical profile should prevent misdiagnosis. Routine frozen section examination of SNs from melanoma patients is not recommended. The utility of ultrasound to detect SN metastases (confirmed by fine needle biopsy) is currently being investigated. Whereas potentially this may avoid the need for formal sentinel lymphadenectomy and histopathologic evaluation in some patients, the lack of sensitivity of currently available ultrasound technologies to detect the small micrometastases (<2 mm in diameter), that are typically present in most melanoma patients with a positive SN, limits its current role. In the future, other techniques, such as the use of carbon particles or antimony analysis, may better localize the site of metastases within SNs and permit more focused and efficient pathologic examination of SNs. At present, the role of nonhistopathologic methods of SN evaluation, such as reverse transcription polymerase chain reaction (RT-PCR) and magnetic resonance spectroscopy, remains unclear, and these techniques require further evaluation.

What is a positive sentinel lymph node in a breast cancer patient? A practical approach

Sentinel lymph node (SN) biopsy has become increasingly used for the staging of breast carcinoma, resulting in the upstaging of this disease, and this has led to concerns with regard to what should be considered a positive SN. Factors influencing the positive staging of an SN include metastasis size, the method used for metastasis detection, the definition of metastasis and the individual pathologist. Until evidence to the contrary emerges, an SN should be considered positive if metastases (nodal involvement >0.2mm in the largest dimension) are detected in it by histology. A target size should be identified, and SNs, as the most likely sites of nodal metastases, should be searched systematically to find (nearly) all of the targeted metastases. The European guidelines for SN assessment have set two such target sizes: as a minimum, all metastases >2mm should be identified, and optimally all micrometastases should also be sought.

Pathological Evaluation of Sentinel Lymph Nodes

The sentinel lymph nodes are the most likely site of nodal metastasis. Their focused analysis results in upstaging cancers, although the extra yield from a more intensive work-up is generally dominated by micrometastases and isolated tumor cells. Nodal staging is generally done to reflect systemic spread of solid tumors and guide treatment accordingly. However, in general, the two processes of haematogenous and lymphogenic spread are not causally interrelated, and the extrapolation from low-volume nodal involvement to systemic involvement and therapeutic consequences of this extrapolation are still under investigation.

Sentinel lymph nodes in breast cancer after 10 years: rethinking basic principles

New techniques and treatments in medicine occasionally take on a life of their own. Sometimes, an idea's use is inherently obvious from the outset, sometimes not, in which case it becomes technology in search of an application. Identification of sentinel lymph nodes in breast cancer is a combination of these two options: to some extent the technique has been overused and its results overinterpreted. 10 years after the procedure's introduction and general acceptance, a few issues still deserve further discussion despite much published work on this topic. Use of sentinel-lymph-node identification has been extended to other organ systems, yet not all the lessons learned in the breast might apply to other sites. Review of the theory behind the technique and breast cancer experience to date is important. Many of the published controversies about sentinel lymph nodes in breast cancer can be resolved by consideration of the basic ideas underlying the procedure, which is the aim of this Essay.

The value of immunohistochemistry in sentinel lymph node histopathology in breast cancer

The optimal protocol for the histopathological examination of sentinel lymph nodes (SLNs) in breast cancer has not been determined. The value of more detailed examination using immunohistochemistry (IHC) is controversial. A total of 476 SLNs from 216 patients were reviewed. Sentinel lymph nodes were sectioned at three levels at 100 μm intervals and stained with haematoxylin and eosin (H&E). If the H&E sections showed no evidence of metastasis, then the three serial sections were stained with a murine monoclonal anti-cytokeratin antibody (CAM 5.2). Metastatic deposits were classified as macrometastasis (>2.0 mm), micrometastasis (0.2–2.0 mm) or isolated tumour cells (ITC, <0.2 mm). Of the 216 patients, 56 (26%) had metastasis as identified by H&E. Immunohistochemistry detected metastatic deposits in a further nine patients (4%), of whom four (2%) had micrometastasis and five (2%) had ITC only. Those cases with micrometastases were all, on review, visible on the H&E sections. Immunohistochemistry detects only a small proportion of metastasis in SLNs. All metastatic deposits identified by IHC were either micrometastasis or ITC. Until the prognostic significance of these deposits has been determined, IHC may be of limited value in the histopathological examination of SLNs.

Sentinel lymph nodes in cancer of the oral cavity -- isolated tumour cells

BACKGROUND

Sentinel lymph node biopsy, step sectioning and immunohistochemistry have changed detection of tumour deposits. Isolated tumour cells (ITC) are detected more frequently than earlier because of a changed level of detection.

METHODS

A total of 108 sentinel lymph nodes from 30 patients with T1/T2 cN0 oral cancer were re-classified histologically to find possible ITC and to describe technical pitfalls.

RESULTS

Primarily we found metastatic spread in 12 of 108 sentinel lymph nodes: five macrometastasis and seven micrometastasis. After re-classification, we found seven lymph nodes with macrometastasis, five with micrometastasis and two with ITC.

CONCLUSION

The ITC are probably precursors of micrometastasis waiting to grow and should be treated as such. Benign inclusions and dendritic cells did not cause problems, but can mimic ITC.

Sentinel lymph nodes and breast carcinoma: analysis of 70 cases by frozen section

BACKGROUND

The sentinal node biopsy (SNB) is a reliable method for determining the status of the regional lymph nodes in patients with breast cancer. SNB technology is evolving rapidly, but no standardization has yet been accomplished. The aim of this study is to discuss the accuracy of this procedure and the optimal method for identifying micrometastases.

METHODS

We collected data from 70 women with primary invasive breast carcinoma who underwent SNB for breast cancer. We examined two frozen sections levels from each half of each lymph node, as well as a cytology imprint before arriving at the frozen section diagnosis. Immunohistochemistry with pancytokeratin (AE1/AE3) was done on the paraffin sections. For the association between the lymph node size and the possibility of metastases, Student's t test was used and a P value of less than 0.05 was regarded as significant.

RESULTS

The number of patients with metastases in SNB was 19, from which 15 cases were correctly diagnosed in frozen sections/imprints and four cases were false negative. The axillary toilet from all cases with SNB metastases smaller than 2 mm showed no additional positive nodes. Lymph node diameter showed a significant association with sentinel node status (P<0.0001).

CONCLUSION

Frozen section examination of SNB from patients with breast carcinoma is both specific (100%) and sensitive (79%). Diagnosis of lobular carcinoma can be difficult, and may require immunohistochemistry with cytokeratin for diagnosis. Small metastases in a non-optimal frozen section may be difficult to discern. Cytology imprints add nothing to the diagnosis.

Surgical pathological staging of breast cancer by sentinel lymph node biopsy with special emphasis on the histological work-up of axillary sentinel lymph nodes

Axillary nodal status assessed by traditional histological methods is a proven independent prognostic factor in breast cancer. Sentinel lymph node biopsy is a surgical pathologic staging procedure that not only allows the selective removal of the most likely sites of lymphogenic metastases, but also enables upstaging of breast carcinoma by detecting nodal involvement undetected by standard methods of nodal staging. This review highlights the upstaging potential of sentinel node biopsy. It also suggests that incomplete reporting of the pathological methods may make the comparisons of results from different studies difficult. The article also describes a few methods that have been claimed optimal but are probably not, and it formulates basic considerations for building up a histological protocol that can identify all metastases larger than 2 mm, which are of unquestionable prognostic relevance. These considerations are also useful for the detection of micrometastases. Issues of pathological reporting of sentinel nodal findings are also highlighted, with emphasis on the lack of standardization and on the differentiation of isolated tumor cells from micrometastases. Finally the stepwise building up of our current histology protocol and our experience gained since the introduction of sentinel node biopsy in 1997 is also briefly summarized.

Pathological Evaluation of Sentinel Lymph Nodes for Breast Cancer

Recently, sentinel lymph node (SLN) biopsy has been employed to avoid unnecessary lymph node dissection, because SLN negativity for carcinoma metastases may imply an extremely low possibility of non-SLN involvement. Pathological evaluation is essential, but standardized procedures have not yet been determined. Intraoperative consultation, either by frozen section (multiple slices are desirable) or touch imprint cytology, are usually very useful. Their accuracy, however, is variable and depends on the procedures used, but specificity is characteristically 100%, and the missed metastatic focus is always quite minute. After fixation, multiple sections, immunohistochemistry, and their combination will be able to detect small metastatic foci more frequently. The clinical significance of small or submicro- or occult metastases have not yet been clarified, and further investigations are needed. If the SLN is positive for carcinoma metastases, both the procedure for detection and the size of the metastatic focus should be clarified on the pathological reports.

Antimony concentrations in nodal tissue can confirm sentinel node identity

The sentinel node biopsy procedure is a highly accurate method of staging patients with cutaneous melanoma and the tumor-harboring status of sentinel nodes is the most important prognostic factor. For the procedure to provide accurate prognostic information, however, it is essential that 'true' sentinel nodes are removed and examined thoroughly. A technique to confirm sentinel node identity may reduce the false-negative rate of the procedure. We have found that antimony (originating from the antimony sulfide colloid used for preoperative lymphoscintigraphy in our institution) can be measured in tissue sections of sentinel nodes using inductively coupled plasma mass spectrometry. The aims of this study were to determine whether antimony concentrations can be used to confirm that removed sentinel nodes are 'true' sentinel nodes and to differentiate sentinel nodes from nonsentinel nodes. In all, 24 patients who had both a tumor-positive sentinel node and a tumor-negative nonsentinel node removed from one regional node field during the same operation, were identified. Tissue sections (50 microm) thick were cut from archival paraffin blocks of each of the sentinel nodes and nonsentinel nodes. Antimony concentrations in the tissue sections were measured using inductively coupled plasma mass spectrometry. The median and mean concentrations of antimony in parts per billion were 0.526 and 1.198, respectively (range 0.020-7.596) in the sentinel nodes, and 0.043 and 0.123 (range 0-0.800) in the nonsentinel nodes (P = 0.004). In four of the 24 pairs, both the presumed sentinel nodes and the nonsentinel nodes had very low antimony levels (less than 0.18 parts per billion), suggesting that nodes designated as sentinel nodes may not have been 'true' sentinel nodes. It is concluded that determination of antimony concentrations within sentinel nodes using the highly sensitive method of inductively coupled plasma mass spectrometry can confirm the identity of sentinel nodes and validate the sentinel node technique.

A model for determining the optimum histology of sentinel lymph nodes in breast cancer

AIMS

To create and use a geometrical model for sentinel lymph node (SLN) histopathology in breast cancer.

METHODS

The model involves a spherical metastasis randomly situated in an SLN. Two extreme situations are taken as the starting points. In one of these, the metastasis is seen in its largest dimension, whereas in the other it is only just visible, approximating 0 mm in size. Intermediate positions are analysed, with different metastasis sizes and different distances between the levels assessed by histology.

RESULTS

The findings suggest that sections taken 1 mm apart afford a reasonable means of identifying almost all metastases measuring > 2 mm (referred to as macrometastases here). For nearly all micrometastases to be identified correctly according to the current TNM definitions (that is, metastases > 0.2 mm), a step sectioning protocol with levels of 250 microm or 200 microm would be adequate.

CONCLUSIONS

SLNs are the most likely sites of nodal metastasis. Macrometastases are of recognised prognostic relevance so that all should be identified, preferably correctly as macrometastases; an assessment of levels 1 mm apart appears satisfactory and sufficient for this aim. SLNs also offer an ideal method for the study of the significance of micrometastases; for this, step sections separated by 200 or 250 microm are a good choice.