Reverse transcription-polymerase chain reaction assay for multiple mRNA markers in the detection of breast cancer metastases in sentinel lymph nodes

RNA cytometry of single-cells using semi-permeable microcapsules

Analytical tools for gene expression profiling of individual cells are critical for studying complex biological systems. However, the techniques enabling rapid measurements of gene expression on thousands of single-cells are lacking. Here, we report a high-throughput RNA cytometry for digital profiling of single-cells isolated in liquid droplets enveloped by a thin semi-permeable membrane (microcapsules). Due to the selective permeability of the membrane, the desirable enzymes and reagents can be loaded, or replaced, in the microcapsule at any given step by simply changing the reaction buffer in which the microcapsules are dispersed. Therefore, complex molecular biology workflows can be readily adapted to conduct nucleic acid analysis on encapsulated mammalian cells, or other biological species. The microcapsules support sequential multi-step enzymatic reactions and remain intact under different biochemical conditions, freezing, thawing, and thermocycling. Combining microcapsules with conventional FACS provides a high-throughput approach for conducting RNA cytometry of individual cells based on their digital gene expression signature.

A clinical diagnostic test on the detection of sentinel lymph node metastasis in breast neoplasms using a 1-step RT-PCR

BACKGROUND

Currently, assessment of sentinel lymph node (SLN) requires cytology, hematoxylin-eosin (HE), and immunohistochemistry (IHC). However, routine pathological slides still suffer from certain sampling errors and have time limitations. This study sought to investigate the sensitivity and specificity of SLN detection by reverse transcription-polymerase chain reaction (RT-PCR), which quantifies the expression of mammaglobin and cytokeratin-19 genes to determine SLN status.

METHODS

The RT-PCR detection of cycles threshold (CT) values has a direct relationship with the lymph node metastasis. This study prospectively collected 256 sentinel lymph nodes from 150 patients diagnosed with breast cancer between August and November 2017. In the detection of metastases in lymph nodes, molecular markers can be verified at the cell-level and tissue-level of tumor cells. In this study, IHC results were used as the gold standard for judging sentinel lymph node status.

RESULTS

(I) According to the established cell models, as the lymph nodes in tumor cells increase, RT-PCR CT values decrease. (II) 83 lymph nodes were first collected, and the interpretation criteria for the molecular detection results were determined based on the IHC results. (III) The statistical analysis showed that the sensitivity of the RT-PCR was 80.49% and the specificity was 91.55%. The positive predictive and negative predictive values were 64.71% and 96.06%, respectively. There was no significant difference between RT-PCR detection and IHC detection (P=0.076). Statistical chi-square analysis also showed that the difference between intraoperative freezing and immunohistochemistry was statistically significant (P=0.000). There was a statistically significant difference between intraoperative freezing and RT-PCR detection (P=0.000). RT-PCR detection is more sensitive than intraoperative frozen detection, and is closer to the results of immunohistochemistry.

CONCLUSIONS

RT-PCR had objective and rapid output advantages, and was proven to be true and reliable. RT-PCR detection can not only rapidly assess sentinel lymph node status in breast cancer patients during surgery, but its accuracy is also close to that of IHC. Correctly determine whether to perform axillary lymph node dissection and improve the survival rate of patients.

Detection of mammagloblin by RT-PCR as a biomarker for lymph node metastasis in breast cancer patients: A systematic review and meta-analysis

Background

This meta-analysis presents evidence regarding the diagnostic accuracy of mammaglobin detected using the RT-PCR technique, related to the presence of sentinel node metastasis in breast cancer patients.

Methods

The following databases were consulted: Cochrane, Lilacs, Scielo, Hinary, PubMed, Elsevier, Embase, ProQuest, the Universidad del Rosario´s Centro de Recursos Para el Aprendizaje y la Investigación (CRAI-UR) [Resource Center for Learning and Research], and the Google Scholar search engine. The quality of the studies was assessed using the QUADAS-2 and CASpe tools. The selected studies presented the necessary data to calculate diagnostic validity index of mammaglobin detection using RT-PCR, compared with the reference standard test. Global values for the sensitivity, specificity, positive predictive value, negative predictive value, probability ratios, diagnostic ORs, and summary ROC curves of this meta-analysis were obtained using the Meta-DiSc 1.4 program.

Results

Initially, 731 articles were obtained; but only 25 were included in the meta-analysis. Sensitivity was 84% (95% CI: 83% - 86%), and specificity was 92% (95% CI: 91% - 93%). Positive and negative predictive values were 9.26 (95% CI: 6.47–13.26) and 0.17 (95% CI: 0.13–0.23), respectively. The diagnostic OR was 66.34 (95% CI: 42.52–103.52). The predictive area under the sROC curve was 94.78 (Q = 0.8876).

Conclusions

The evaluated diagnostic index showed that the expression of the mammaglobin biomarker has diagnostic prediction for detecting lymph node metastasis in breast cancer patients, when analyzed using RT-PCR, although more than 50% heterogeneity was found.

Anti-hMAM monoclonal antibodies evaluated in breast and non-breast tissues for differential diagnosis implication

PURPOSE

Human mammaglobin (hMAM) is a breast tissue-specific marker that may have potency for the diagnosis of breast cancer. However, there is a lack of commercialization of anti-hMAM antibody made in China.

METHODS

Immunoreactivities of 2 self-made monoclonal anti-hMAM antibodies, MEF521 and MDA822, were evaluated by immunohistochemistry staining and compared with imported monoclonal antibody ab81611. A total of 48 cases of primary breast cancers, 36 cases of benign or normal breast tissues, 52 cases of lymph nodes or organ metastases from breast cancer, and 90 cases of non-breast primary carcinoma tissues were analyzed.

RESULTS

All 3 anti-hMAM antibodies showed high positive expression of hMAM in primary breast cancers, benign, and normal breast tissues. The positive ratio for MEF521 (33.3%) or MDA822 (44.4%) was much higher than that of ab81611 (16.7%) in lymph node metastasis from breast cancer (p = 0.038). There was no correlation between hMAM expression and clinicopathologic features of breast cancer in the 3 groups of antibodies. In 90 cases of non-breast primary carcinoma tissues, no hMAM-positive ones were observed in the MEF521 or MDA822 group, but 48 (53.3%) in the ab81611 group were positive, indicating that breast tissue specificity of the 2 self-made anti-hMAM monoclonal antibodies much higher than that of ab81611 (p<0.001).

CONCLUSIONS

Our results showed that MDA822 and MEF521 are more specific to breast cancer as measured by means of immunohistochemistry. Therefore, the 2 self-made anti-hMAM antibodies may have good prospects for clinical application in the differential diagnosis of breast tumor and breast cancer metastases.

One-Step Nucleic Acid Amplification in Breast Cancer Sentinel Lymph Node: A Single Institutional Experience and a Short Review

Sentinel lymph node (SLN) examination is a standard in breast cancer patients, with several methods employed along its 20 years history, the last one represented by one-step nucleic acid amplification (OSNA). The latter is a intra-operative molecular assay searching for CK19 mRNA as a surrogate of metastatic cells. Our 3 years experience with OSNA (1122 patients) showed results overlapping those recorded in the same institution with a morphological evaluation (930 patients) of SLN. In detail, the data of OSNA were almost identical to those observed with standard post-operative procedure in terms of patients with positive SLN (30%) and micrometastatic/macrometastatic involvement of SLN (respectively, 38–45 and 62–55%). By contrast, when OSNA was compared to the standard intraoperatory procedure, it was superior in terms of accuracy, prompting the use of this molecular assay as a very valid, and reproducible for intra-operative evaluation of SLN. Further possibilities prompting the use of OSNA range from adhesion to quality control programs, saving of medical time, ability to predict, during surgery, additional nodal metastasis, and molecular bio-banking.

Treatment of sentinel node-positive breast cancer

Sentinel node biopsy has become well accepted as a minimally invasive means of accurately staging the axilla in breast cancer patients. Patients with metastases in the sentinel node(s) have traditionally proceeded to completion of axillary node dissection, whereas patients who are node negative can be spared the morbidity of this procedure. Recently, there has been some debate as to what constitutes node-positive disease and whether patients with metastasis in the sentinel node(s) require completion axillary dissection. This review addresses the controversies regarding the management of sentinel node-positive breast cancer patients.

Reliability of whole sentinel lymph node analysis by one-step nucleic acid amplification for intraoperative diagnosis of breast cancer metastases

OBJECTIVE

To assess the reliability of using the One-Step Nucleic Acid Amplification (OSNA) assay as a single test on whole sentinel lymph nodes (SLN) as a method of intraoperative diagnosis and staging of SLNs in breast cancer.

BACKGROUND

Combining histological and molecular assessment of metastasis on the same SLN may not fully reproduce the actual load of cancer cells present in the SLN and create problems in decisions regarding axillary dissection.

METHODS

Selection criteria for the whole SLN OSNA test required that the primary tumor expressed CK19 in more than 80% of tumor cells. Imprint cytology analysis of SLNs was performed together with the OSNA.

RESULTS

Of the 279 patients enrolled for SLN evaluation, 123 gave consent to the OSNA protocol and 156 to the standard histology. Thirteen patients were excluded from OSNA evaluation because of low CK19 gene expression in the primary tumor; only 2.3% were truly negative. The kappa of concordance between the imprint cytology and OSNA results was 0.52. The rate of macrometastases determined by OSNA was 11% versus 20% determined by histology, whereas the rate of OSNA-micrometastases (18%) was significantly higher than that determined by histology (8%). The rate of SLN-negative cases was similar between the 2 protocols. Macrometastases correlated with the presence of vascular invasion in both protocols. The rate of axillary lymph node metastases was consistent with SLN tumor load.

CONCLUSIONS

Intraoperative OSNA assay performed on the whole SLN gave objective and reproducible results that were useful for directing decisions regarding axillary dissection and for accurately defining the SLN stage.

Diagnostic performance of one-step nucleic acid amplification for intraoperative sentinel node metastasis detection in breast cancer patients

The purpose of this prospective multicenter study was to assess one-step nucleic acid amplification (OSNA) for intraoperative sentinel lymph node (SLN) metastasis detection in breast cancer patients, using final histology as the reference standard. OSNA results were also compared to intraoperative histology SLN evaluation and to standard clinicopathological risk markers. For this study, fresh SLNs were cut in four blocks, and alternate blocks were used for OSNA and histology. CK19 mRNA copy number was categorized as strongly positive, positive or negative. Positive histology was defined as presence of macrometastasis or micrometastasis. When discrepancies occurred, the entire SLNs were subjected to histological studies and the node lysates to additional molecular studies. Five hundred three SLN samples from 233 patients were studied. Mean time to evaluate two SLNs was 40 min. Sensitivity per patient was 91.4% (95% CI, 76.9-98.2%), specificity 93.3% (95% CI, 88.6-96.6%), positive likelihood ratio 13.7 and negative likelihood ratio 0.1. Sensitivity was 63.6% for frozen sections and 47.1% for touch imprint cytology. Both methods were 100% specific. Positive histology and positive OSNA were significantly associated with highest clinical stage, N1 status and vascular invasion; and OSNA results correlated with HER2/neu status and benefited patients with negative histology. These findings show that OSNA assay can allow detection of SLN metastasis in breast cancer patients intraoperatively with a good sensitivity, thus minimizing the need for second surgeries for axillary lymph node detection.

Intraoperative assessment of sentinel lymph nodes in breast cancer

Background

Sentinel lymph node biopsy (SLNB) reduces the morbidity of axillary clearance and is the standard of care for patients with clinically node-negative breast cancer. The ability to analyse the sentinel node during surgery enables a decision to be made whether to proceed to full axillary clearance during primary surgery, thus avoiding a second procedure in node-positive patients.

Methods

Current evidence for intraoperative sentinel node analysis following SLNB in breast cancer was reviewed and evaluated, based on articles obtained from a MEDLINE search using the terms ‘sentinel node’, ‘intra-operative’ and ‘breast cancer’.

Results and conclusion

Current methods for evaluating the sentinel node during surgery include cytological and histological techniques. Newer quantitative molecular assays have been the subject of much recent clinical research. Pathological techniques of intraoperative SLNB analysis such as touch imprint cytology and frozen section have a high specificity, but a lower and more variably reported sensitivity. Molecular techniques are potentially able to sample a greater proportion of the sentinel node, and could have higher sensitivity.

Sentinel Lymph Node Biopsy in Breast Cancer

The axillary lymph node status is the most reliable prognostic indicator of recurrence and overall survival in patients with breast cancer. The current standard surgical procedure for the management of invasive breast cancer is the complete removal of the cancer with total axillary clearance. However, recently, selective sentinel lymph node mapping and biopsy is gaining acceptance as a useful and accurate staging procedure, as it is minimally invasive. The sentinel lymph node is the first node into which a primary cancer drains, and is thus the first node to be involved by metastases. Patients whose sentinel nodes are negative for breast cancer metastases, can be spared a more extensive axillary lymph node dissection, with reduction in the postoperative morbidity. Sentinel node mapping is usually performed by intradermal or peritumoral injection of a combination of blue dye and radiotracer. Sentinel node examination is sometimes done intraoperatively, by imprint cytology and frozen sections, for an immediate assessment, to plan the extent of surgery at a single sitting. Permanent sections of the sentinel node are studied by serial sectioning, and immunohistochemistry for cytokeratin is done to detect micrometastases which are frequently missed on hematoxylin and eosin (H&E)-stained sections. The various aspects of sentinel node examination, and its role to decide further management in patients with ductal carcinoma-in-situ, and in other clinical settings, are discussed in this review.

Molecular markers of breast axillary lymph node metastasis

In breast cancer, axillary lymph node status is one of the most important prognostic variables and a crucial component to the staging system. Several clinico-histopathological parameters are considered to be strong predictors of metastasis; however, they fail to accurately classify breast tumors according to their clinical behavior and to predict which patients will have disease recurrence. Methods based on genome-wide microarray analyses have been used to identify molecular markers with respect to the development of axillary lymph node metastasis. Most of these markers can be detected in the primary tumors, which can potentially lead to the ability to identify patients at the time of diagnosis who are at high risk for lymph node metastasis, allowing for early intervention and more suitable adjuvant treatments.

Comparability of different pathologic protocols in sentinel lymph node evaluation: an analysis of two step-sectioning methods for the same patients with breast cancer

CONTEXT

The pathologic protocol for sentinel lymph node evaluation has yet to be standardized. Results from previous studies are troublesome to compare because they have been conducted on different sets of subjects with cancer.

OBJECTIVE

To compare the detection of sentinel lymph node metastases by using step-sectioning methods at 20-microm and 150-microm intervals for the same patient with primary breast cancer.

DESIGN

A total of 186, initially tumor-negative sentinel lymph nodes from a group of 80 patients with breast cancer were included. For all nodes, each paraffin block was cut serially to produce a total of 10 levels: 5 consecutive levels of sections for each of the 20-microm and 150-microm intervals. The nodal findings obtained at these intervals on hematoxylin-eosin and cytokeratin slides were compared by using the McNemar test.

RESULTS

The overall detection rate for sentinel lymph node metastasis at intervals of 20 microm and 150 microm was 27.5% (22/80) and 20% (16/80), respectively. The overall agreement between the 20-microm and 150-microm sections was 82.5%. No macrometastasis was missed by either method. At the 20-microm interval, 2 cases of micrometastasis were missed, while 10 cases of isolated tumor cells were missed at the 150-microm interval. However, no statistical difference was observed for the final sentinel lymph node results with either method. (McNemar test, P = .18 for case-based results and P = .052 for nodal-based results).

CONCLUSIONS

The 20-microm and 150-microm interval step-sectioning methods produce comparable results for detection of metastatic deposits in sentinel lymph nodes.

Technical limits of comparison of step-sectioning,immunohistochemistry and RT-PCR on breast cancer sentinel nodes: a study on methacarn-fixed tissue

The optimal pathological assessment of sentinel nodes (SLNs) in breast cancer is a matter of debate. Currently, multilevel histological evaluation and immunohistochemistry (IHC) are recommended, but alternative RT-PCR procedures have been developed. To assess the reliability of these different procedures, we devised a step-sectioning protocol at 100 micron-intervals of 74 SLNs using methacarn fixation. mRNA was extracted from sections collected from levels 4 to 5. Mammaglobin, CEA and CK19 were used for RT-PCR. mRNA extraction was successful in 69 SLNs. Of these, 7 showed macrometastases (>2mm), 2 showed micrometastases (<2 mm) and 7 showed isolated tumour cells (ITC) by IHC. RT-PCR was positive for the three markers in 6 of 7 macrometastases and in 1 of 2 micrometastases. In the 2 RT-PCR negative cases, metastases were detected only on sections distant from those analysed by RT-PCR. CEA and/or CK19 were positive by RT-PCR in 3 of 7 ITC and in 23 morphologically negative SLNs. In conclusion, the main goal of our study was to show that the use of alternate sections of the same sample for different procedures is the key reason for the discrepancies between molecular and morphological analyses of SLN. We believe that only prospective studies with quantitative mRNA analysis of specific metastatic markers on the whole lymph node can elucidate the utility of molecular assessments of SLN.

Molecular detection of lymph node metastases in breast cancer patients: results of a multicenter trial using the one-step nucleic acid amplification assay

PURPOSE

Accurate assessment of metastasis in sentinel lymph nodes (SLN) of breast cancer is important but involves a heavy workload for the pathologist. We conducted a multicenter clinical trial in Japan to evaluate a new automated assay system for cytokeratin 19 mRNA, the one-step nucleic acid amplification (OSNA) assay (Sysmex), to detect lymph node metastasis of breast cancer.

EXPERIMENTAL DESIGN

Surgically obtained axillary lymph nodes were sectioned into four pieces, two of which were examined with the OSNA assay. The other two adjacent pieces were examined with H&E and immunohistochemical staining for cytokeratin 19. Serial sections at 0.2-mm intervals were used in trial 1 to determine the specificity of the OSNA assay, and three pairs of sections cut from the sliced surfaces of the pieces were used in trial 2 to compare the accuracy of the OSNA assay with that of a routine pathologic examination for SLNs in Japan.

RESULTS

In trial 1, the sensitivity and specificity were 95.0% [95% confidence interval (95% CI), 75.1-99.9%] and 97.1% (95% CI, 91.8-99.4%), respectively, for 124 axillary lymph nodes obtained from 34 patients. In trial 2, the agreement between findings of the assay and of the pathologic examination was 92.9% (95% CI, 90.1-95.1%) for 450 axillary lymph nodes obtained from 164 patients.

CONCLUSION

The OSNA assay can detect lymph node metastasis as accurately as can conventional pathology and thus can be an effective addition to or alternative for rapid intraoperative examination of SLNs.

Axillary metastases in breast cancer patients with negative sentinel nodes: a follow-up of 3548 cases

PREMISES: Sentinel node biopsy (SNB) in patients with breast carcinoma accurately predicts the axillary node status. However, in some 4-7% of patients with negative sentinel nodes, the remaining axillary nodes harbour cancer cells.

OBJECTIVE

Our purpose was the long-term observation of a large number of patients who did not receive axillary dissection after a negative sentinel node biopsy, in order to evaluate the incidence of overt axillary metastases.

METHODS

Patients (3548) treated from 1996 to 2004, with negative sentinel nodes not submitted to axillary dissection, were followed up to 11 years with a median follow-up of 48 months.

RESULTS

Three hundred and sixteen unfavourable events occurred among the 3548 patients, 196 of which (5.5%) related to primary breast carcinoma. Thirty one cases of overt axillary metastases were found (0.9%): they received total axillary dissection and 27 of them are at present alive and well. The 5-year overall survival rate of the whole series was 98%.

CONCLUSIONS

Patients with negative sentinel node biopsy not submitted to axillary dissection show, at follow-up, a rate of overt axillary metastases lower than expected.

Sentinel lymph node as a target of molecular diagnosis of lymphatic micrometastasis and local immunoresponse to malignant cells

The sentinel lymph node (SLN) is defined as the lymph node(s) first receiving lymphatic drainage from the site of the primary tumor. The histopathological status of SLN is one of the most significant predictors of recurrence and overall survival for most clinical stage I/II solid tumors. Recent progress in molecular techniques has demonstrated the presence of micrometastatic tumor cells in SLN. There is now a growing body of data to support the clinical relevance of SLN micrometastasis in a variety of solid tumors. Increasing the sensitivity of occult tumor cell detection in the SLN, using molecular-based analysis, should enable a more accurate understanding of the clinical significance of various patterns of micrometastatic nodal disease. The establishment of metastasis to SLN might not be simply reflected by the flow dynamics of lymphatic fluid that drains from the primary site to the SLN, and the transportation of viable cancer cells. Recent studies have demonstrated that primary tumors can actively induce lymphangiogenesis and promote SLN metastasis. Moreover chemokine receptors in tumor cells may facilitate organ-specific tumor metastasis in many human cancers and some experimental models. In contrast, recent clinical and preclinical studies regard SLN as the first lymphoid organ to respond to tumor antigenic stimulation. SLN dramatically show morphological, phenotypical and functional changes that indicate immune suppression by tumor cells. The immune suppression in SLN results in failure of prevention or eradication of tumor metastasis. The mechanism of immunomodulation remains unclear; however, several regulatory molecules produced by tumor cells and tumor-associated macrophages or lymphocytes are likely to be responsible for inducing the immune suppression in SLN. Further studies may develop a novel immunotherapy that overcomes tumor-induced immune suppression and can prevent or eradicate SLN metastasis.

Comparative evaluation of an extensive histopathologic examination and a real-time reverse-transcription-polymerase chain reaction assay for mammaglobin and cytokeratin 19 on axillary sentinel lymph nodes of breast carcinoma patients

OBJECTIVE

To assess the accuracy of a commercially available real-time reverse-transcription-polymerase chain reaction assay for mammaglobin and cytokeratin 19 mRNAs [GeneSearch Breast Lymph Node (BLN) Assay, Veridex LLC, Warren, NJ] in the detection of axillary sentinel lymph nodes (SLNs) metastases in patients with breast carcinoma.

SUMMARY BACKGROUND DATA

Because of the lack of standardized and widely accepted protocols for a truly accurate histopathologic examination of SLN, the relative merits of alternative assays based on the identification of tumor specific mRNA markers deserve further assessment.

METHODS

: A prospective series of 293 consecutive SLNs from 293 patients was evaluated. The BLN assay results were compared with those of an extensive histopathologic examination of the entire SLNs performed on serial frozen sections cut at 40 to 50 microm intervals.

RESULTS

The BLN assay correctly identified 51 of 52 macrometastatic and 5 of 20 micrometastatic SLNs, with a sensitivity of 98.1% to detect metastases larger than 2 mm, 94.7% for metastases larger than 1 mm, and 77.8% for metastases larger than 0.2 mm. The overall concordance with histopathology was 90.8%, with specificity of 95.0%, positive predictive value of 83.6%, and negative predictive value of 92.9%. When the results were evaluated according to the occurrence of additional metastases to non-SLN in patients with histologically positive SLNs, the assay was positive in 33 (91.7%) of the 36 patients with additional metastases and in 22 (66.6%) of the 33 patients without further echelon involvement.

CONCLUSIONS

The sensitivity of the reverse-transcription -polymerase chain reaction assay is comparable to that of the histopathologic examination of the entire SLN by serial sectioning at 1.5 to 2 mm.

Sentinel node biopsy: interpretation and management of patients with immunohistochemistry-positive sentinel nodes and those with micrometastases

The sentinel node procedure is an adequate tool to identify lymph node metastasis in breast cancer. Sentinel nodes are generally examined with greater attention mainly to exclude, as reliably as possible, lymph node metastasis. To achieve this, many protocols are used, resulting in different rates of micrometastasis or isolated tumor cells encountered. Since the prognostic significance of isolated tumor cells or micrometastasis in the sentinel nodes, and the risk of further axillary lymph node involvement in patients with isolated tumor cells, is uncertain and at most limited, these findings may pose difficulties for clinicians in clinical decision making. Protocols that identify lymph node metastasis, from which the clinical relevance is known, are warranted. Unnecessary lymph node dissections should be avoided.

Molecular oncology: current trends in diagnostics

Applications of molecular diagnostics to oncology have been slow to make their way to the clinical laboratory. While numerous genes and mutation spectra have been found to be involved in tumorigenesis, it is only recently that these findings begin to become useful in a clinical setting. Building on the technical knowledge obtained from molecular infectious disease testing, new instruments and assays have been developed to answer similar questions regarding qualitative, quantitative and genotyping issues. In this manuscript we describe two current examples of clinical molecular diagnostic applications, the assessment of BCR–ABL in chronic myelogenous leukemia patients and the detection of tumor cells in the sentinel lymph nodes of breast cancer patients, to demonstrate the role of molecular techniques in a routine clinical setting.

One-step nucleic acid amplification for intraoperative detection of lymph node metastasis in breast cancer patients

PURPOSE

Detection of sentinel lymph node (SLN) metastasis in breast cancer patients has conventionally been determined by intraoperative histopathologic examination of frozen sections followed by definitive postoperative examination of permanent sections. The purpose of this study is to develop a more efficient method for intraoperative detection of lymph node metastasis.

EXPERIMENTAL DESIGN

Cutoff values to distinguish macrometastasis, micrometastasis, and nonmetastasis were determined by measuring cytokeratin 19 (CK19) mRNA in histopathologically positive and negative lymph nodes using one-step nucleic acid amplification (OSNA). In an intraoperative clinical study involving six facilities, 325 lymph nodes (101 patients), including 81 SLNs, were divided into four blocks. Alternate blocks were used for the OSNA assay with CK19 mRNA, and the remaining blocks were used for H&E and CK19 immunohistochemistry-based three-level histopathologic examination. The results from the two methods were then compared.

RESULTS

We established CK19 mRNA cutoff values of 2.5 x 10(2) and 5 x 10(3) copies/muL. In the clinical study, an overall concordance rate between the OSNA assay and the three-level histopathology was 98.2%. Similar results were obtained with 81 SLNs. The OSNA assay discriminated macrometastasis from micrometastasis. No false positive was observed in the OSNA assay of 144 histopathologically negative lymph nodes from pN0 patients, indicating an extremely low false positive for the OSNA assay.

CONCLUSION

The OSNA assay of half of a lymph node provided results similar to those of three-level histopathology. Clinical results indicate that the OSNA assay provides a useful intraoperative detection method of lymph node metastasis in breast cancer patients.

Correlation between molecular metastases in sentinel lymph nodes of breast cancer patients and St Gallen risk category

AIMS

To evaluate the clinical significance of tumour metastases detected using real-time reverse transcription-PCR (RT-PCR) in sentinel lymph nodes (SLN) of breast cancer patients.

METHODS

Sixty-seven patients with T1-T2 primary breast cancer were included in a prospective study. SLN were analysed for the presence of metastatic tumour cells using standard histopathology staining, immunochemistry (IHC) and multimarker real-time RT-PCR assay for mammaglobin (MMG), carcinoembryonic antigen (CEA) and cytokeratin-19 (CK19) mRNA expression. Correlations between molecular metastases and traditional clinicopathological prognostic factors, including St Gallen risk categories were studied.

RESULTS

Of the 67 patients, 15 (22.3%) had one or more pathology-positive SLN. Five (9.6%) pathology-negative SLN were positive by IHC and 19 (36.5%) by RT-PCR. Of note, RT-PCR analysis was also positive in all cases with pathology- or IHC-positive SLN. MMG was the most informative tumour marker in the panel. Molecularly detected metastases were significantly associated with intermediate St Gallen risk category (p=0.023).

CONCLUSION

Molecular staging of SLN using real-time RT-PCR for early breast cancer could serve as a useful complement to standard clinicopathological risk factors. Studies with long-term follow-up are necessary to define the impact of molecular metastases on disease free survival and overall survival.

Identification of differentially expressed genes in mouse hepatocarcinoma ascites cell line with low potential of lymphogenous metastasis

AIM: To identify genes differentially expressed in mouse hepatocarcinoma ascites cell line with low potential of lymphogenous metastasis.

METHODS: A subtracted cDNA library of mouse hepatocarcinoma cell line with low potential of lympho-genous metastasis Hca-P and its synogenetic cell line Hca-F with high metastatic potential was constructed by suppression subtracted hybridization (SSH) method. The screened clones of the subtracted library were sequenced and GenBank homology search was performed.

RESULTS: Fifteen differentially expressed cDNA fragments of Hca-P were obtained which revealed 8 known genes, 4 expressed sequence tags (ESTs) and 3 cDNAs showed no homology.

CONCLUSION: Tumor metastasis is an incident involving multiple genes. SSH is a useful technique to detect differentially expressed genes and an effective method to clone novel genes.

Assessing the status of axillary sentinel lymph nodes of breast carcinoma patients by a real-time quantitative RT-PCR assay for mammaglobin 1 mRNA

The aim of the study was to assess the accuracy of a real-time quantitative RT-PCR (qRT-PCR) assay for mammaglobin 1 mRNA in the detection of metastatic breast cancer in axillary sentinel lymph nodes (SLN), comparing the results with those of qualitative RT-PCR assays and of an extensive histopathological examination. A retrospective series of 81 SLN from 72 patients and a validation series of 61 SLN from 61 patients were evaluated. In the retrospective series, the qRT-PCR assay was positive for 23 (28.4%) of the 81 SLN. The overall concordance with histopathology was 93.8%, with a sensitivity of 90.9%, a specificity of 94.9%, a positive predictive value (PPV) of 87% and a negative predictive value (NPV) of 96.6%. In the same series, qualitative RT-PCR showed an overall concordance with histopathology of 86.4%, a sensitivity of 72.7%, a specificity of 91.5%, a PPV of 76.2% and a NPV of 90%. In the validation series, including 23 patients with pure in situ carcinoma, the real-time qRT-PCR assay showed an overall concordance with the histopathologic findings of 93.4%, with a sensitivity of 75.0%, a specificity of 94.7%, a PPV of 50.0% and a NPV of 98.2%. We conclude that real-time qRT-PCR assays for mammaglobin 1 are more sensitive and specific that qualitative RT-PCR assays for the detection of metastatic breast carcinoma in axillary SLN, but it should not be regarded as a possible substitute for an extensive histopathological scrutiny of the SLN in the clinical practice.

RT-PCR determination of maspin and mammaglobin B in peripheral blood of healthy donors and breast cancer patients

BACKGROUND

The aim of the present study was to evaluate the accuracy of two markers, maspin and mammaglobin B, singly or in combination, to detect breast cancer. To define better the potential and limits of the two markers for diagnostic purposes, blood positivity was analyzed in relation to clinical, pathological and biological tumor characteristics.

PATIENTS AND METHODS

The markers were determined in peripheral blood (PB) samples from 27 healthy donors and 140 previously untreated patients using nested reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

Positivity for maspin in blood samples was observed in 24% of patients with an 89% specificity. For mammaglobin B, positivity was observed in 7% of patients and never in healthy donors. The presence of maspin was correlated with cell proliferation of the primary tumor (P = 0.015), whereas mammaglobin B positivity correlated with pathological stage (P = 0.013). The presence of either marker was significantly related to nodal status.

CONCLUSIONS

Our results indicate that the two markers in association could represent a potentially useful non-invasive tool to detect breast cancer. The validation of these markers as indicators of high risk of relapse is ongoing in a series of patients with an adequate follow-up.

Pathologic examination of the axillary sentinel lymph nodes in patients with early-stage breast carcinoma: current and resolving controversies on the basis of the European Institute of Oncology experience

Several controversial aspects of sentinel lymph node biopsy (SLNB) for patients with early-stage, node-negative breast carcinoma have been dealt with and resolved in the past decade since its introduction. Unfortunately, however, there is still no consensus on how best to examine sentinel lymph nodes (SLN) histologically. As a consequence, the protocols for SLN examination are remarkably variable in different institutions, leading to a very poor reproducibility of the data stemming from investigations on series of patients whose SLNs have been evaluated according to diverse protocols. Patient outcomes, however, can be optimised only by standardization of the whole procedure of SLNB, with particular reference to the histopathologic scrutiny. Lack of a standardized histopathologic protocol likely derives also from the uncertainties about the clinical implications of minimal lymph node involvement (isolated tumour cells and micrometastases) with regard both to the risk of additional metastases to non-sentinel lymph nodes of the same basin and to the prognostic value for patients' survival. This review aims at highlighting some of the controversial issues of the histopathologic examination of the SLNs, including the number of sections and cutting intervals, the use of immunohistochemistry and the role of molecular biology assays.

Identification and characterization of optimal gene expression markers for detection of breast cancer metastasis

Sentinel lymph node (SLN) status is highly predictive of overall axillary lymph node involvement in breast cancer. Historically, SLN-positive patients have undergone axillary lymph node dissection in a second surgery. Intraoperative SLN analysis could reduce the cost and complications of a second surgery; however, existing histopathological methods lack standardization and exhibit poor sensitivity. Rapid molecular methods may lead to improved intraoperative diagnosis of SLN metastasis. In this study, we used a genome-wide gene expression analysis of breast and other tissues to identify seven putative markers for detecting breast cancer metastasis. We assessed the utility of these markers for identifying clinically actionable metastases in lymph nodes through reverse transcriptase-polymerase chain reaction analysis of SLNs from 254 breast cancer patients. Polymerase chain reaction signals were compared to pathology on a per-patient basis. The optimal two-gene combination, mammaglobin and cytokeratin 19, detected clinically actionable metastasis in breast SLNs with 90% sensitivity and 94% specificity. Application of stringent criteria for identifying presumptive hematoxylin- and eosin-positive samples increased sensitivity and specificity to 91 and 97%, respectively. This study represents the first comprehensive demonstration of the utility of gene expression markers for detecting clinically actionable breast metastases. An intraoperative molecular assay using these markers has the potential to significantly reduce second surgeries for patients undergoing SLN dissection.

Combined application of RT-PCR and immunohistochemistry on paraffin embedded sentinel lymph nodes of prostate cancer patients

The detection of tumor cells in the sentinel lymph node (SLN) is of great importance for the prognosis of cancer patients. At present, immunohistochemistry and RT-PCR for tumor marker expression are the most sensitive techniques available for this analysis. However, so far, most RT-PCR-based analyses of SLNs have been performed on fresh material, excluding a direct comparison with the (immuno)histologic results. In our view, this does not entirely aid routine diagnosis. We established an efficient method for RNA extraction and RT-PCR from paraffin sections of SLNs from prostate cancer patients and compared the results with the (immuno)histologic data of adjacent sections. Amplifiable RNA was obtained from 133 SLNs of 68 prostate cancer patients. Correlation of PSA-specific RT-PCR with (immuno)histologic findings showed a positive and negative predictive value of 83% and 100%, respectively, for the prostate cancer patients investigated. Four of 12 patients with biochemical relapse, but without (immuno)histologically detectable tumor cells were RT-PCR-positive for PSA. We found that single sections of paraffin-embedded SLNs are suitable for routinely performed RT-PCR. Combined with (immuno)histology, PSA-specific RT-PCR is a revealing supplementary technique for the detection of tumor cells in SLNs of prostate cancer patients.

Sentinel node biopsy in breast cancer: early results in 953 patients with negative sentinel node biopsy and no axillary dissection

Sentinel node biopsy in patients with breast carcinoma accurately predicts the axillary nodal status. However, in some 6% of patients with negative sentinel nodes the remaining axillary nodes harbour metastases. Our purpose was to observe a large number of patients who did not undergo an axillary dissection after a negative sentinel node biopsy for the appearance of overt axillary metastases. 953 patients treated from 1996 to 2000, with negative sentinel nodes not submitted to axillary dissection, were followed-up to 7 years, with a median follow-up of 38 months. Fifty-five unfavourable events occurred among the 953 patients, 37 (4%) related to the primary breast carcinoma. Three cases of overt axillary metastases were found: they received total axillary dissection and are presently alive and well. The 5 year overall survival rate of the whole series was 98%. Patients with negative sentinel node biopsies not submitted to axillary dissection show during follow-up a rate of overt axillary metastases that is lower than that expected.

Molecular detection of micrometastatic breast cancer in histopathology-negative axillary lymph nodes correlates with traditional predictors of prognosis: an interim analysis of a prospective multi-institutional cohort study

OBJECTIVE

We sought to establish the clinical relevance of micrometastatic disease detected by reverse transcription polymerase chain reaction (RT-PCR) in axillary lymph nodes (ALN) of breast cancer patients.

BACKGROUND

The presence of ALN metastases remains one of the most valuable prognostic indicators in women with breast cancer. However, the clinical relevance of molecular detection of micrometastatic breast cancer in sentinel lymph nodes (SLN) and nonsentinel ALN has not been established.

METHODS

Four hundred eighty-nine patients with T1-T3 primary breast cancers were analyzed in a prospective, multi-institutional cohort study. ALN were analyzed by standard histopathology (H&E staining) and by multimarker, real-time RT-PCR analysis (mam, mamB, muc1, CEA, PSE, CK19, and PIP) designed to detect breast cancer micrometastases.

RESULTS

A positive marker signal was observed in 126 (87%) of 145 subjects with pathology-positive ALN, and in 112 (33%) of 344 subjects with pathology-negative ALN. In subjects with pathology-negative ALN, a positive marker signal was significantly associated with traditional indicators of prognosis, such as histologic grade (P = 0.0255) and St. Gallen risk category (P = 0.022). Mammaglobin was the most informative marker in the panel.

CONCLUSION

This is the first report to show that overexpression of breast cancer-associated genes in breast cancer subjects with pathology-negative ALN correlates with traditional indicators of disease prognosis. These interim results provide strong evidence that molecular markers could serve as valid surrogates for the detection of occult micrometastases in ALN. Correlation of real-time RT-PCR analyses with disease-free survival in this patient cohort will help to define the clinical relevance of micrometastatic disease in this patient population.

Mammaglobin: a candidate diagnostic marker for breast cancer

Mammaglobin, known for its mammary tissue specificity, has been discussed as a promising diagnostic marker in breast cancer for almost 10 years. In particular, the application of mammaglobin RT-PCR to detect disseminated breast cancer cells has been reported. More than 25 publications evaluate the detection of mammaglobin mRNA in lymph node, blood, and bone marrow specimens of breast cancer patients. Recently, structural details about the mammaglobin complex have been discovered, and these findings can be implemented to optimize detection of the secreted protein. This review summarizes the findings of almost 50 published studies and the current knowledge about the diagnostic utility of mammaglobin.

Mammaglobin is associated with low-grade, steroid receptor-positive breast tumors from postmenopausal patients, and has independent prognostic value for relapse-free survival time

PURPOSE

The tumor mRNA expression levels of mammaglobin, a novel breast-specific and breast cancer-associated marker, were correlated with disease outcome in 280 patients with primary breast cancer.

PATIENTS AND METHODS

Mammaglobin expression levels were assessed by quantitative reverse transcriptase polymerase chain reaction in frozen tumor tissue from breast cancer patients with a median age of 60 years (range, 30 to 88 years) and a median follow-up of 85 months (range, 2 to 169 months).

RESULTS

High expression levels were associated with low-grade tumors (P =.018), with positive estrogen and progesterone receptor status (P <.001), and postmenopausal status (P =.010). In the analysis of all patients, low tumor mammaglobin expression levels predicted an early relapse both in Cox univariate (hazard ratio [HR], 0.52; 95% CI, 0.34 to 0.79; P =.002) and multivariate regression analyses corrected for the traditional prognostic factors (HR, 0.55; 95% CI, 0.35 to 0.88; P =.012). The association of mammaglobin expression with the rate of relapse was particularly favorable in patients who received adjuvant tamoxifen treatment (HR, 0.35; 95% CI, 0.17 to 0.71; P =.004).

CONCLUSION

These results demonstrate that the assessment of the tumor mRNA expression level of the breast-specific protein mammaglobin could be useful to stratify patients for individual adjuvant treatment strategies.

Histopathologic examination of axillary sentinel lymph nodes in breast carcinoma patients

The axillary sentinel lymph node biopsy (SLNB) has gained increasing popularity as a novel surgical approach for staging patients with breast carcinoma and for guiding the choice of adjuvant therapy with minimal morbidity. Patients with negative SLNB represent a subset of breast carcinoma patients with definitely better prognosis, because their pN0 status is based on a very thorough examination of the sentinel lymph nodes (SLNs), with a very low risk of missing even small micrometastatic deposits, as compared with routine examination of the 20 or 30 lymph nodes obtained by the traditional axillary clearing. The histopathologic examination of the SLNs may be performed after fixation and embedding in paraffin, or intraoperatively on frozen sections. Whatever is the preferred tracing technique and surgical procedure, the histopathologic examination of each SLN must be particularly accurate, to avoid a false-negative diagnosis. Unfortunately, because of the lack of standardised guidelines or protocols for SLN examination, different institutions still adopt their own working protocols, which differ substantially in the number of sections cut and examined, in the cutting intervals (ranging from 50 to more than 250 microm), and in the more or less extensive use of immunohistochemical assays for the detection of micrometastatic disease. Herein, a very stringent protocol for the examination of the axillary SLN is reported, which is applied either to frozen SLN for the intraoperative diagnosis, and to fixed and embedded SLN as well.

Quantitative evaluation of metastases in axillary lymph nodes of breast cancer

We have established a highly sensitive and quantitative reverse transcriptase–polymerase chain reaction (RT–PCR) method to detect axillary lymph node metastases of breast cancer. Amplifying cytokeratin 19 (CK19) mRNA transcripts using real-time TaqMan PCR made it possible to quantify axillary metastatic burden. Metastases in 358 axillary lymph nodes obtained from 23 breast cancers of 22 patients were investigated by conventional haematoxylin and eosin (H&E) staining, immunohistochemical staining and quantitative RT–PCR assay. The detection rates of axillary lymph node metastasis using H&E staining, immunohistochemistry and RT–PCR assay were 4.5, 5.9 and 13.1%, respectively. RT–PCR assay was the most sensitive of these three methods for detecting lymph node metastases. Cytokeratin 19 mRNA expression values of both histologically and immunohistochemically positive lymph nodes were significantly higher than the values for lymph nodes judged to be negative by both histological and immunohistochemical methods (P<0.0001), and those of histologically negative, but immunohistochemically positive lymph nodes were significantly higher than the values for lymph nodes judged to be negative by both histological and immunohistochemical methods (P<0.0001). Furthermore, metastatic rates of sentinel nodes were higher than the rates of nonsentinel lymph nodes as measured by all three methods. These results indicate that quantitative RT–PCR assay is a sensitive and reliable method for detecting lymph node metastasis. Furthermore, quantification of metastases in sentinel lymph nodes by quantitative RT–PCR assay may be useful to assess the entire axillary burden of breast cancer patients.

The molecular detection of micrometastatic breast cancer

BACKGROUND

The rapid evolution of molecular technology and novel markers provides the opportunity to establish a more effective means to detect micrometastatic breast cancer. Given the controversies concerning application and clinical relevance, this review critically evaluates the current status of these molecular staging technologies.

DATA SOURCES

Breast cancer literature addressing (1). molecular detection methodologies (immunohistochemistry, reverse transcriptase polymerase chain reaction, and microarray analysis); (2). specific tissue applications such as lymph nodes, bone marrow aspirate, and peripheral blood; (3). expert commentary concerning the clinical applications and pitfalls of these technologies; and (4). recent data from our molecular diagnostics laboratory.

CONCLUSIONS

Molecular detection technologies such as reverse transcriptase polymerase chain reaction and microarray analyses are being developed that will likely have future application as cancer diagnostics. Further work is needed to establish assays that are validated by prospective clinical studies. Early identification of clinically relevant disease could lead to new treatment or staging approaches for breast cancer.

Application of immunofluorescence for intraoperative evaluation of sentinel lymph nodes in patients with breast carcinoma

BACKGROUND

Sentinel lymph node (SLN) sampling is used to predict axillary lymph node (AxLN) metastasis in patients with breast carcinoma; AxLN sampling can be avoided in SLN-negative patients. Multistep sectioning and immunohistochemistry are reported to increase the sensitivity of micrometastasis detection. The authors used immunofluorescence (IF) staining with cytokeratin (CK) antibodies for intraoperative evaluation of touch imprints from multistep sections of SLNs.

METHODS

A combined total of 150 SLNs from 69 patients who had breast carcinoma and underwent surgery were analyzed. SLNs were sectioned at 2 mm intervals, and touch imprints subsequently were prepared. After ethanol fixation, slides were incubated with fluorescein isothiocyanate-conjugated CK and propidium iodide and then subjected to microwave irradiation for 3 minutes. Finally, fluorescence microscopy was used to evaluate slides for the presence or absence of metastatic disease.

RESULTS

Metastatic disease was identified in 36 (24.0%), 26 (17.3%), 32 (21.3%), and 31 (20.7%) of 150 lymph nodes using IF staining, Papanicolaou (Pap) staining, immunocytochemical (ICC) staining, and hematoxylin and eosin (H and E) staining, respectively. The sensitivities of IF, Pap, ICC, and H and E staining were 94.6%, 70.3%, 86.5%, and 83.8%, respectively. Except for IF staining (specificity, 99.1%), each method had a specificity of 100%. The accuracy rates for IF, Pap, ICC, and H and E staining were 98.0%, 92.7%, 96.7%, and 96.0%, respectively.

CONCLUSIONS

IF is a rapid, highly sensitive, and highly specific staining technique by which touch imprints can be used to intraoperatively evaluate SLNs in patients with breast carcinoma.

Pathological work-up of sentinel lymph nodes in breast cancer. Review of current data to be considered for the formulation of guidelines

Controversies and inconsistencies regarding the pathological work-up of sentinel lymph nodes (SNs) led the European Working Group for Breast Screening Pathology (EWGBSP) to review published data and current evidence that can promote the formulation of European guidelines for the pathological work-up of SNs. After an evaluation of the accuracy of SN biopsy as a staging procedure, the yields of different sectioning methods and the immunohistochemical detection of metastatic cells are reviewed. Currently published data do not allow the significance of micrometastases or isolated tumour cells to be established, but it is suggested that approximately 18% of the cases may be associated with further nodal (non-SN) metastases, i.e. approximately 2% of all patients initially staged by SN biopsy. The methods for the intraoperative and molecular assessment of SNs are also surveyed.

Mammaglobin-A is a tumor-associated antigen in human breast carcinoma

BACKGROUND

Mammaglobin-A is an attractive target for immune-based therapy for patients with breast cancer because of its exclusive expression in breast cancer. In this study, we attempted to identify immunogenic T cell epitopes restricted by human leukocyte antigen (HLA)-A2 in mammaglobin-A protein.

METHODS

To identify HLA-A2-restricted immunogenic epitopes from mammaglobin-A, 7 candidate peptides were synthesized and tested for immunogenicity. Each peptide was tested for binding to HLA-A2 in a HLA-A2 stabilization assay. Furthermore, T lymphocytes from 7 healthy donors and 1 patient with breast cancer received 3 weekly stimulations with autologous peptide-pulsed dendritic cells. Stimulated T cells were tested for specific recognition of peptide and tumor cells by interferon-gamma enzyme-linked immunosorbent assay.

RESULTS

HLA-A2 binding assays showed that all designed peptides could bind to HLA-A2. Two of the 7 peptides (MAM3 and MAM7) successfully induced peptide-specific T cells. However, only MAM3-specific T cells recognized the mammaglobin overexpressing breast cancer cell line, MDA415 transfected with HLA-A2. In contrast, MAM3-specific T cell did not recognize wild type MDA415 or MDA415 transfected with HLA-A24, or the mammaglobin negative, HLA-A2 positive breast cancer cell line, MCF-7.

CONCLUSIONS

Mammaglobin-A-derived peptide, MAM3, can induce mammaglobin-A-specific immunity and could be useful for vaccine strategies for patients with breast cancer.

Mammaglobin expression in gynecologic malignancies and malignant effusions detected by nested reverse transcriptase-polymerase chain reaction

The detection of micrometastatic disease remains a challenge for the diagnosis and monitoring of malignant disease. RT-PCR for human mammaglobin (hMAM) was recently shown to provide a sensitive method for assessing circulating breast cancer cells in peripheral blood. This study was aimed at investigating hMAM expression in normal and malignant tissue from the female genital tract and the prostate as well as in malignant effusions derived from gynecologic malignancies. hMAM expression was analyzed with nested RT-PCR in 152 samples of normal (n = 73) and malignant epithelial tissues (n = 79) and in 33 specimens of various normal mesenchymal tissue types. We found hMAM expression was not restricted to the normal mammary gland and breast carcinoma but was also detectable in most specimens of benign and malignant epithelial tissue from the ovary (97% versus 95%), uterus (both 100%), and cervix (91% versus 90%). Notably, hMAM expression was also found in benign prostatic hyperplasia (45%) and in prostate cancer (55%). A much lower expression rate was found in various normal and benign mesenchymal tissues (12%). In keeping with our previous data, hMAM expression was absent in all control samples (n = 124) of peripheral blood and bone marrow from healthy volunteers and patients with hematologic malignancies. In pleural or peritoneal effusions (n = 42) from patients with carcinomas of the breast, endometrium, or ovary, hMAM positivity was noticed in the majority of cases (74%), whereas only 52% of the specimens were cytologically positive for tumor cells. In conclusion, hMAM expression assessed by nested RT-PCR is a sensitive molecular marker for detecting micrometastatic tumor spread into pleural effusions and ascites from patients with breast cancer and various other gynecologic neoplasms.

Pathological and molecular assessment of sentinel lymph nodes in solid tumors

Sentinel nodes (SNs) are the first set of nodes to receive drainage and cancer cells from a primary tumor. While there may be a single SN, frequently there are one to three or more SNs. The development of sentinel node surgery over the last decade has led to dramatic changes in the surgical approach to regional nodes draining solid tumors. The surgeon can now identify, to a level of accuracy previously impossible, the regional nodes most likely to be involved with cancer in any individual patient. This new capability comes at a cost; the principles guiding the extent of nodal surgery must be completely re-examined. The extent of surgical resection required to achieve each of the goals of regional node surgery-(1) establishing prognosis, (2) obtaining regional control, and (3) improving overall survival-may no longer be simply the default "regional node resection" and may vary depending on the clinical goals. Inseparable from this new surgical technology is the methodology employed for pathologic evaluation of SNs. It is critical that pathologists and clinicians conduct definitive clinical research directed toward defining the role and impact that SN surgery has on each of these surgical goals.