Pathologic Evaluation of Lymph Nodes in Breast Cancer: Contemporary Approaches and Clinical Implications

The presence of detected metastases in locoregional lymph nodes of women with breast cancer is an important prognostic variable for cancer staging, prognosis, and treatment planning. Systematic and standardized lymph node evaluation with gross and microscopic protocols designed to detect all macrometastases larger than 2.0 mm is the appropriate objective based on clinical outcomes evidence. Pathologists will detect smaller micrometastases and isolated tumor cell clusters (ITCs) by random chance but will also leave similar sized metastases undetected in paraffin blocks. Although these smaller metastases have prognostic significance, they are not predictive of recurrence for chemotherapy naïve patients. Thus, protocols to reliably detect metastases smaller than 2.0 mm are not required or recommended by guidelines. Women with T1-T2 breast cancer with a clinically negative axilla but with 1 or 2 pathologically positive sentinel nodes now have alternative options including observation and axillary irradiation and do not require completion axillary dissection.

Clinical effect of the pathological axillary assessment method in breast cancer without clinical nodal metastasis

BACKGROUND

This study aimed to assess the clinical effect of the pathological axillary assessment method in breast cancer without clinical lymph node metastasis.

METHODS

Data of patients with clinically node-negative breast cancer were retrospectively reviewed. The study period was divided into early (January 2000-July 2007) and late (August 2007-December 2014) periods based on the pathological assessment method used (single-sectional and detailed multi-sectional lymph node processing). In the late period, lymph nodes were evaluated at six levels including immunohistochemistry on each 1.5-2 mm interval section. The axillary diagnostic accuracy and role of chemotherapy were assessed.

RESULTS

In 1698 patients, 27 isolated tumor cells (ITCs), 39 micrometastases, and 205 macrometastases were noted. The sensitivity for pathological N0 diagnosis was dependent on clinical T stage, Tis (97.8%), T1 (83.0%), T2 (74.2%), T3 (54.5%), and T4 (63.6%). ITCs and micrometastases were detected only in the late period, and 84.7% and 91.6% of cases in the early and late period, respectively, did not have macrometastases. The 5-year disease-free interval (DFI) rates were 95.2% in node-negative cases, 98.4% in ITCs/micrometastases, and 91.4% in macrometastases (P < 0.001). In multivariate analysis, the predictor for DFI was estrogen receptor negativity (P = 0.013). Chemotherapy did not improve DFI in patients with node-positive breast cancer.

CONCLUSIONS

The detailed multi-sectional pathological assessment of axillary lymph nodes detected ITCs and micrometastases. Implementation of chemotherapy should not be based on the minimal nodal metastasis and this type of serially nodal sectioned processing had little clinical significance.

Immunohistochemistry and Reverse Transcriptase Polymerase Chain Reaction on Sentinel Lymph Nodes can Improve the Accuracy of Nodal Staging in Breast Cancer Patients

In this study the nodal staging sensitivity of sentinel lymph node biopsy (SLNB) with detailed pathological and molecular biological examination has been investigated and compared to that of axillary lymph node dissection (ALND) with routine histological evaluation. Sentinel lymph nodes (SLNs) were removed by the dual-agent injection technique in 68 patients with primary, clinically node-negative breast cancer. Forty-seven patients had negative SLNs according to hematoxylin and eosin (H&E) staining. These H&E-negative SLNs were serially sectioned and examined at 250 μm levels by anticytokeratin immunohistochemistry (IHC). In 14 patients the SLNs were also investigated by cytokeratin 20 (CK20) reverse transcriptase polymerase chain reaction (RT-PCR). SLNB with IHC increased the node-positive rate by 26% (by 40% in tumors less than or equal to 2 cm in size (pT1) and by 9% in tumors more than 2 cm but less than or equal to 5 cm in size (pT2)). The sensitivity of SLNB with IHC was superior to that of ALND with routine histology in pT1 tumors and identical in pT2 tumors. The concordance between histology and RT-PCR was only 21%, and in two of three cases with positive histological results RT-PCR was negative. In conclusion, SLNB with detailed pathological and/or molecular biological evaluation can improve the sensitivity of regional staging. ALND can probably be abandoned in patients with pT1 SLN-negative breast cancer. Further prospective studies are required to determine the clinical significance of these detailed SLN evaluation techniques, but at present these methods are still investigational.

Minimal Involvement of Sentinel Lymph Node in Breast Carcinoma: Prevailing Concepts and Challenging Problems

Sentinel lymph node biopsy has attained “standard of care” status in the management of breast carcinoma. However, the pathological interpretation and clinical consequences of “minimally involved” sentinel lymph nodes remain controversial. Herein, we present some of the complex and challenging pathological problems inherent in this evolving setting. Clearly, at least some of our current concepts regarding “minimally involved” sentinel lymph nodes need reappraisal.

Comparison of the Diagnostic Value Between Real-Time Reverse Transcription-Polymerase Chain Reaction Assay and Histopathologic Examination in Sentinel Lymph Nodes for Patients With Gastric Carcinoma

OBJECTIVES

Sentinel lymph node (SLN)-based diagnosis in gastric cancers has shown varied sensitivities and false-negative rates in several studies. Application of the reverse transcription-polymerase chain reaction (RT-PCR) in SLN diagnosis has recently been proposed.

METHODS

A total of 155 SLNs from 65 patients with cT1-2, N0 gastric cancer were examined. The histopathologic results were compared with results obtained by real-time RT-PCR for detecting molecular RNA (mRNA) of cytokeratin (CK)19, carcinoembryonic antigen (CEA), and CK20.

RESULTS

The sensitivity and specificity of the multiple marker RT-PCR assay standardized against the results of the postoperative histological examination were 0.778 (95% confidence interval [CI], 0.577-0.914) and 0.781 (95% CI, 0.700-0.850), respectively. In comparison, the sensitivity and specificity of intraoperative diagnosis were 0.819 (95% CI, 0.619-0.937) and 1.000 (95% CI, 0.972-1.000), respectively. The positive predictive value of the multiple-marker RT-PCR assay was 0.355 (95% CI, 0.192-0.546) for predicting non-SLN metastasis, which was lower than that of intraoperative diagnosis (0.813, 95% CI, 0.544-0.960).

CONCLUSIONS

The real-time RT-PCR assay could detect SLN metastasis in gastric cancer. However, the predictive value of the real-time RT-PCR assay was lower than that of precise histopathologic examination and did not outweigh that of our intraoperative SLN diagnosis.

Comparative analysis between multilevel sectioning with conventional haematoxylin and eosin staining and immunohistochemistry for detecting nodal micrometastases with stage I and II colorectal cancers

Management of patients with stage II colorectal carcinomas remains challenging as 20 - 30% of them will develop recurrence. It is postulated that these patients may harbour nodal micrometastases which are imperceptible by routine histopathological evaluation. The aims of our study were to evaluate (1) the feasibility of multilevel sectioning method utilizing haematoxylin and eosin stain and immunohistochemistry technique with cytokeratin AE1/AE3, in detecting micrometastases in histologically-negative lymph nodes, and (2) correlation between nodal micrometastases with clinicopathological parameters. Sixty two stage I and II cases with a total of 635 lymph nodes were reviewed. Five-level haematoxylin and eosin staining and one-level cytokeratin AE1/AE3 immunostaining were performed on all lymph nodes retrieved. The findings were correlated with clinicopathological parameters. Two (3.2%) lymph nodes in two patients (one in each) were found to harbour micrometastases detected by both methods. With cytokeratin AE1/AE3, we successfully identified four (6.5%) patients with isolated tumour cells, but none through the multilevel sectioning method. Nodal micrometastases detected by both multilevel sectioning and immunohistochemistry methods were not associated with larger tumour size, higher depth of invasion, poorer tumour grade, disease recurrence or distant metastasis. We conclude that there is no difference between the two methods in detecting nodal micrometastases. Therefore it is opined that multilevel sectioning is a feasible and yet inexpensive method that may be incorporated into routine practice to detect nodal micrometastases in centres with limited resources.

A mathematical approach to the optimal examination of lymph nodes

There is no scientific evidence to support the idea that serial sectioning along the short axis of the lymph node is superior to a single bisection along the long axis. We mathematically evaluated methods of lymph node dissection and applied the result to six lymph nodes that had produced false negative results at the time of frozen examination. We simplified the geometry of a lymph node to that of a three-dimensional ellipse and compared two different cutting methods. Let A be the cross-sectional area obtained through a single bisection along the long axis, and let B be the sum of the cross-sectional areas of n fragments obtained via serial cutting along the short axis. The smallest n (n*) that makes a B larger than A can be calculated. n* = [3L + √9L² + 16S²)/4S]. ([α], the smallest integer greater than or equal to α; L, long axis; S, short axis). The probabilities of tumor detection when the node is bisected along the long axis (P(D(A)|E)) and when serially cut along the short axis (P(D(B)|E)) are as follows. P(D(A)|E = {(3/2)S² - 3ST + T²}T/(S - T)³. and P(D(B)|E) = (n - 1){(1 + 1/n)L² - 3LT + T²}T/(L - T)³. (T, size of the tumor cell cluster). According to these formulas, three out of six lymph nodes were not examined in the most appropriate manner.

[Intraoperative molecular assessment of sentinel nodes in the breast cancer using the Gene Search BLN Assay technique: our experience about 126 patients]

INTRODUCTION

Intraoperative molecular assay Gene Search BLN Assay (BLN) detects sentinel lymph node (SLN) metastasis in breast cancer. Our objective was to compare BLN to the definitive conventional histologic methods and to experiment the management of BLN in routine.

MATERIAL AND METHODS

Each SLN was cut into alternate slabs. Half slabs were analysed with the intraoperative BLN molecular method, and the other slabs with the definitive histologic method.

RESULTS

Two hundred and thirty four SLN have been analysed (124 patients). Thirty-five SLN had metastasis for 29 patients (23.4%). BLN correctly identified 28 patients. Two cases of discordance between BLN and standard method were found, probably explained by a sample bias. The sensibility of BLN is 96.4%, the sensitivity is 99%, the predictive positive value is 96.4%, the predictive negative value is 99% and the concordance is 98.4%. The surgery time increases and there is a need to adapt the theatre organization accordingly.

CONCLUSION

The Gene Search BLN Assay gives a great interest for the patient, the surgeon and the pathologist because it increases the quality of the intraoperative analysis by comparison with the intraoperative conventional histology.

[Intraoperative determination of axillary node metastasis by RT-PCR]

The intraoperative determination of axillary node micrometastasis according to the Rapid GeneSearch Breast Lymph Node (BLN) is based on RT-PCR (mRNA of mammaglobine and CK19) detects metastases > 0.2 mm.

PATIENTS AND METHODS

Eighty-three pts between November 2007 and June 2008 were included (33 from Centre Jean-Perrin and 50 from Centre Oscar-Lambret). Lymph nodes were cut in 2 mm slices, and 1 out of 2 was examined with BLN; the others were examined by imprints then histological exam with immunohistochemistry.

RESULTS

Forteen pts had micro- or macrometastasis. Seven were positive with intraoperative imprints including six macrometastasis and one micrometastasis; seven were positive with BLN and seven at histological exam with two cases of discordance. Sensitivity was 92%, specificity 98%. Positive predictive value 92%, and negative predictive value 98%. The median time for intraoperative determination was 40 minutes for 2 SLN.

DISCUSSION

Half each lymph node is study by each method. This explains the discordances observed. Limit of BLN is the absence of CTI detection; however there is no consensus about the necessity of axillary clearance in such a case.

CONCLUSION

In this series BLN reduces axillary clearance and improves comfort patients.

Metastasis detection in sentinel lymph nodes: comparison of a limited widely spaced (NSABP protocol B-32) and a comprehensive narrowly spaced paraffin block sectioning strategy

The National Surgical Adjuvant Breast and Bowel Project B-32 trial is examining whether patients with initially negative sentinel lymph nodes (SLNs) who have occult metastases detected on deeper levels and cytokeratin immunohistochemistry stains are at risk for regional or distant metastases. The experimental B-32 protocol was designed to detect metastases larger than 1.0 mm by examining sections approximately 0.5 and 1.0 mm deeper into the paraffin blocks (2 levels; wide spacing). This pilot quality assurance study compares detection rates to a comprehensive protocol designed to detect metastases larger than 0.2 mm (multilevel; narrow spacing). All SLNs were sectioned grossly at close to 2.0 mm and all sections embedded in paraffin blocks. For clinical treatment, a single hematoxylin and eosin section was examined from each block. For 54 cases with 1 to 5 SLNs and all SLNs negative, additional cytokeratin immunohistochemistry sections were evaluated every 0.18 mm through the block until no tissue remained. Twenty of 176 (11.4%) blocks harbored occult metastases; the B-32 protocol detected metastases in 11 blocks (6.3%) and 9 additional blocks (5.1%) with metastases were detected on sections that would not have been evaluated (P=0.002; correlated proportions). Median number of levels examined per block on the comprehensive protocol was 11 (range: 3 to 26); the B-32 protocol was fixed at 2 levels (median 2; range: 1 to 2). Median thickness of node sections in the block was 2.1 mm (range: 0.7 to 4.8 mm) and the modal thickness was 2.3 mm. Although more comprehensive sectioning of SLNs detects additional micrometastases, the data suggest diminishing returns and reduced cost effectiveness for the comprehensive strategy.

Strategies for optimizing pathologic staging of sentinel lymph nodes in breast cancer patients

Due to the extensive pathologic evaluation of the sentinel lymph node (SLN), micrometastases are frequently observed. If micrometastases are clinically relevant, the histopathologic examination of SLNs should be sensitive enough to detect them. The probability of detecting micrometastases was calculated when examining the SLN according to the current Dutch pathology protocol and strategies evaluated to optimize the chance of detection. The dimensions of 20 consecutive axillary SLNs in patients with cT1-2N0 breast cancer were measured. In a mathematical model, the probability of detecting micrometastases in a SLN was calculated. Similarly, strategies to optimize the probability of detecting micrometastases were explored. When applying the pathology guidelines, the calculated probability to detect a micrometastasis was 18% for a 200-microm micrometastasis and 69% for a 2.0-mm metastasis in a median sized SLN. To detect the smallest micrometastasis in a median-sized SLN with a 95% probability, the interval between the sections must be decreased to 200 microm, and 20 levels from both halves must be examined. Given a prognostic significance of micrometastases, our current pathology guidelines are not sensitive enough. The number of sections should be increased, while the interval between cuts should be no more than 200 microm.

Sentinel node staging for breast cancer: intraoperative molecular pathology overcomes conventional histologic sampling errors

BACKGROUND

When sentinel node dissection reveals breast cancer metastasis, completion axillary lymph node dissection is ideally performed during the same operation. Intraoperative histologic techniques have low and variable sensitivity. A new intraoperative molecular assay (GeneSearch BLN Assay; Veridex, LLC, Warren, NJ) was evaluated to determine its efficiency in identifying significant sentinel lymph node metastases (>.2 mm).

METHODS

Positive or negative BLN Assay results generated from fresh 2-mm node slabs were compared with results from conventional histologic evaluation of adjacent fixed tissue slabs.

RESULTS

In a prospective study of 416 patients at 11 clinical sites, the assay detected 98% of metastases >2 mm and 88% of metastasis greater >.2 mm, results superior to frozen section. Micrometastases were less frequently detected (57%) and assay positive results in nodes found negative by histology were rare (4%).

CONCLUSIONS

The BLN Assay is properly calibrated for use as a stand alone intraoperative molecular test.

Management of the axilla in women with breast cancer

The approach towards axillary surgery should be selective and flexible, with its management tailored to patient choice and tumour characteristics, and concordant with local practice guidelines and available resources. Sentinel-lymph-node biopsy has been embraced as a standard of care in many centres around the world and has revolutionised management of the axilla during the past decade. Nonetheless, data for long-term outcomes remain scarce, and there are persistent variations in practice and inconsistencies in methodology. An international perspective has been sought on important issues relating to management of the axilla, which includes not only the indications and techniques for sentinel-lymph-node biopsy, but also lymph-node sampling, axillary-lymph-node dissection, and observation alone. In this Review, we initially present an overview, which focuses on biological models of lymphatic networks within the breast and patterns of tumour dissemination. A set of key questions are posed with preliminary comments from the authors, followed by a series of collective viewpoints from experts within several different countries.

Axillary Lymph Node Nanometastases Are Prognostic Factors for Disease-Free Survival and Metastatic Relapse in Breast Cancer Patients

PURPOSE

Early breast cancer presents with a remarkable heterogeneity of outcomes. Undetected, microscopic lymph node tumor deposits may account for a significant fraction of this prognostic diversity. Thus, we systematically evaluated the presence of lymph node tumor cell deposits<or=0.2 mm in diameter [pN0(i+), nanometastases] and analyzed their prognostic effect.

EXPERIMENTAL DESIGN

Single-institution, consecutive patients with 8 years of median follow-up (n=702) were studied. To maximize chances of detecting micrometastases and nanometastases, whole-axilla dissections were analyzed. pN0 cases (n=377) were systematically reevaluated by lymph node (n=6676) step-sectioning and anticytokeratin immunohistochemical analysis. The risk of first adverse events and of distant relapse of bona fide pN0 patients was compared with that of pN0(i+), pN1mi, and pN1 cases.

RESULTS

Minimal lymph node deposits were revealed in 13% of pN0 patients. The hazard ratio for all adverse events of pN0(i+) versus pN0(i-) was 2.51 (P=0.00019). Hazards of pN1mi and pN0(i+) cases were not significantly different. A multivariate Cox model showed a hazard ratio of 2.16 for grouped pN0(i+)/pN1mi versus pN0(i-) (P=0.0005). Crude cumulative incidence curves for metastatic relapse were also significantly different (Gray's test chi2=5.54, P=0.019).

CONCLUSION

Nanometastases are a strong risk factor for disease-free survival and for metastatic relapse. These findings support the inclusion of procedures for nanometastasis detection in tumor-node-metastasis staging.

Implications of the sentinel lymph node procedure for local and systemic adjuvant treatment

PURPOSE OF REVIEW

The objective of the sentinel lymph node procedure in breast cancer is to perform an accurate axillary staging and provide good local control, while sparing the patients the morbidity of an axillary lymph node dissection. Since its routine clinical use, questions were raised concerning the implications for local and systemic adjuvant treatment. This review provides an update of the recent literature.

RECENT FINDINGS

As a result of a more detailed histopathologic work-up of the sentinel lymph node, higher rates of lymph node metastases are detected. This leads to an upstaging of a subset of node-negative patients and an increase in the overall percentage of node-positive patients. However, the clinical implications of micrometastases and isolated tumor cells remain unclear. Furthermore, sentinel lymph nodes may be found in the internal mammary lymph node chain but the treatment of these nodes is subject of debate.

SUMMARY

Current guidelines recommend axillary lymph node dissection in patients with a positive sentinel node. The surgical removal of the internal mammary lymph node is only indicated in the context of a clinical trial. Radiation therapy of the axilla is an acceptable alternative for patients who refuse an axillary lymph node dissection (clinical trial). The value of radiotherapy to the internal mammary lymph node has never been established. Systemic treatment decisions in patients with a macrometastasis or micrometastasis in the sentinel lymph node follow the guidelines of node-positive patients, whereas in patients with isolated tumor cells only, guidelines for node-negative patients are followed. The results of ongoing clinical trials will be important for the development of further guidelines.

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.

[Optimization of staging in colon cancer using sentinel lymph node biopsy]

Routine determination of the nodal status in colon cancer is strongly dependent on the individual quality and technique of histopathological assessment and surgical lymph node dissection. We evaluated whether sentinel lymph node biopsy (SLNB) could contribute to an improvement in staging. At least one SLN (median n=2) was detected (detection rate 84%) in each of 38 of 45 patients with primary colon cancer. Ten of these 38 were found to have lymph node metastases by HE staining (26%), six of them in the SLN. Nine of the 28 patients that were initially nodal-negative by HE revealed one micrometastasis and eight cases of isolated tumor cells by immunohistochemical (IHC) staining (32% upstaging response). Including the IHC-positive cases, 19 of the 38 patients were nodal-positive (50%), 15 of them with tumor-infiltrated SLN (overall sensitivity of SLNB 79%). Using the dye method, SLNB is clinically practicable and leads in the majority of the patients to the detection of SLN. The selective, intensified histopathological assessment of SLN identifies small tumor cell deposits in a relevant percentage of patients with little and clinically practicable effort.

A concept for the clinical implementation of sentinel lymph node biopsy in patients with breast carcinoma with special regard to quality assurance

The development of standardized and reproducible clinical pathways is an important precondition for quality assurance in medicine, especially if a new method has not yet been ultimately validated. Sentinel lymph node biopsy (SLNB) is a widely accepted new surgical procedure in the treatment of early breast carcinoma. However, numerous steps of the method and details of the technique are not standardized and, thus, hamper quality assurance for SLNB. The German Society of Senology appointed an interdisciplinary consensus committee to work out guidelines for the standardized performance and quality-assured implementation of SLNB on a nationwide, homogeneous standard. The committee consisted of surgeons, gynecologists, radiooncologists, nuclear physicians, oncologists, and pathologists. Relevant questions related to patient selection, lymphatic mapping, surgery, histopathologic work-up, further local and systemic treatment decisions, patient information, training, and follow-up were evaluated with respect to clinical evidence, objectivity, and reproducibility. Clinical pathways were developed on the basis of this analysis. Requirements to the performing institutions and surgeons were defined.

A decision aid for predicting non-sentinel node involvement in women with breast cancer and at least one positive sentinel node

BACKGROUND

Several clinical trials are re-evaluating the management of the axilla after sentinel node (SN) biopsy. Approximately 50-70% of patients with positive SN have no further nodal involvement. Estimates of the risk of non-sentinel node (NSN) involvement would aid decisions regarding further axillary surgery.

METHODS

Clinical and pathological variables for 82 breast cancer patients with metastasis to at least one SN, were used to find independent predictors of the status of NSNs.

RESULTS

NSN metastases were found in 46.3% of patients. In a regression model patient age, proportion of SN replaced by metastasis and number of SNs were independent predictors of NSN status.

CONCLUSION

Data available after SN biopsy allow estimation of the risk of NSN metastases among patients with positive SNs. Individualised estimates of the risk of NSN involvement may facilitate discussions regarding the trade off between the likely benefits of further axillary surgery and the morbidity of this procedure.

Sentinel Lymph Node Micrometastasis as a Predictor of Axillary Tumor Burden

The sentinel lymph node biopsy (SLNB) procedure is an alternative method for assessing the axillary lymph node (ALN) status in patients with breast cancer. The SLNB carries the risk of a false-negative result, with patients harboring positive ALNs in the face of a negative SLNB examination. In addition, the significance of a SLNB with cells identified only with keratin or with deposits less than 0.2 mm remains unresolved. We analyzed our SLNB data over the past 5 years in order to determine the relationship between SLN tumor burden and ALN tumor burden. Pathology files for the past 5 years at Magee-Womens Hospital were searched for all SLNB cases that had an axillary lymph node dissection (ALND). Each SLNB case was reviewed and tabulated for breast tumor size, SLN tumor size, and largest tumor size in the ALND. Correlation and frequency distribution were performed for the status of all SLNs and ALNDs. Patterns of lymph node metastasis were recorded and the sizes of the SLN metastases were reported according to the recent Philadelphia Consensus Conference on Sentinel Lymph Nodes and the revised American Joint Committee on Cancer (AJCC) staging. SLN metastases were classified as immunohistochemistry (IHC) positive if only single keratin-positive cells or clusters were present and were not observed with standard tissue stains, as submicrometastatic (SMM) if tumors were less than 0.2 mm (excluding IHC positive), as micrometastatic if tumors were larger than 0.2 mm but </=2 mm, or as macrometastatic if tumors were larger than 2 mm. A total of 445 patients had both SLNB and ALND. Fifty percent (224/445) of cases were SLN positive, including 58 SLN positive/ALN positive cases and 166 SLN positive/ALN negative cases. Of the 221 patients in the SLN-negative group, 4 were ALN positive (false-negative SLN). The incidence of SLN metastases increased with tumor stage, with the percentage of SLN positives as follows: T1a, 2.1%; T1b, 10.9%; T1c, 51.7%; and T2, 35.3%. There were 4 of 41 patients (10%) with SLNs that were IHC positive that had macrometastases in a solitary ALN. Three of 22 patients (13.6%) that were SMM positive had ALN macrometastasis in a solitary ALN. Four of 49 patients (8.1%) with micrometastatic SLNs had a solitary positive ALN, 3 of which were macrometastases (6.1%). Overall a total of 10 of 112 patients (9.0%) with traditionally defined SLN micrometastases of 2.0 mm or less had a solitary ALN macrometastasis. The vast majority (90%) of these macrometastases were found with T1c and T2 breast tumors. There was a significant difference in the means of SLN tumor sizes for the SLN-positive/ALND-negative (4.5 mm) versus SLN-positive/ALND-positive (10.1 mm) patients, although the range of SLN tumor sizes within each group were similar. There is an increasing incidence of SLN-positive and ALN-positive cases with increasing T stage. Overall in this series, 9% of patients with SLN metastases </=2 mm had a solitary axillary macrometastasis. Ninety percent of these metastases occurred with T1c/T2 breast tumors, indicating the important codependence of T stage. Overall there is a subset of patients who are IHC positive, SMM positive, or micrometastatic positive with ALNs that are macrometastatic who are at risk of harboring axillary macrometastases. Keratin IHC of breast SLNs is useful for defining these subsets.

The new TNM classification and micrometastases

The 6th Edition of the TNM classification is considered with particular reference to the evidence base for the analysis of lymph nodes. The justification for the definition of a micrometastasis is considered and in particular the problems related to describing a node deposit of less than 200 microm as NO. Such a classification in the absence of clear instructions on node examination is of limited value in terms of comparing different centres and even within the same centre. The classification does not embrace the rapid advances in the biology of breast cancer and some of these are considered as possible ways forward. TNM is meant to be pragmatic and evidence based leading to indications for treatment and a uniform approach between centres. In the former it succeeds, but some of the definitions would appear to be based on limited established data.

Intraoperative examination of sentinel lymph nodes by ultrarapid immunohistochemistry

The recently developed method of ultrarapid immunohistochemistry (IHC) was applied to the intraoperative examination of sentinel lymph nodes (SLNs) in breast cancer patients. In a prospective study of 50 patients with invasive breast carcinomas, a total of 60 SLNs were studied. Among them, 33 SLNs from 30 patients were studied intraoperatively using a direct immunoperoxidase method with anticytokeratin antibody clone MNF116. This technique has a turnaround time of less than 20 minutes. Ultrarapid IHC revealed 15 positive SLNs compared to 14 positive SLNs using hematoxylin and eosin (H and E) frozen sections. The one SLN missed in H and E frozen sections presented with cytokeratin-positive isolated tumor cells in the lymph node sinus. After paraffin embedding, H and E-stained serial step sections of the SLN specimens detected another two patients with isolated tumor cells. We also examined the remaining axillary lymph nodes (ALNs) by H and E-stained serial step paraffin sections. From 17 of the 30 patients with positive SLNs, 6 patients also had metastatic involvement of the ALNs of level I or II. Thus ultrarapid IHC was a very sensitive and rapid technique for the intraoperative detection of metastatic involvement of SLNs in breast cancer patients. This technique may be a useful complementary tool for the intraoperative study of SLNs, particularly in tumors that are a diagnostic challenge, such as lobular carcinoma.

Improved immunohistochemical evaluation of micrometastases in sentinel lymph nodes of cutaneous melanoma with 'MCW melanoma cocktail'--a mixture of monoclonal antibodies to MART-1, Melan-A, and tyrosinase

BACKGROUND

MART-1, Melan-A, and Tyrosinase have shown encouraging results for evaluation of melanoma micrometastases in sentinel lymph nodes, as compared to conventionally used S-100 protein and HMB-45. To achieve higher sensitivity, some studies recommend evaluation of three sections, each at intervals of 200 micron. This would mean, routine staining of three adjacent sections in each of the three clusters at intervals of 200 micron, requiring nine slides resulting in added expense. If a cocktail of these antibodies could be used, only one section would be required instead of three generating significant cost savings.

METHODS

We prepared a combination of monoclonal antibodies to these three immunomarkers in optimized dilutions (MART-1, clone M2-7C10, dilution 1:500; Melan-A, clone A103, dilution 1:100; and Tyrosinase, clone T311, dilution 1:50) and designated it as 'MCW melanoma cocktail'. Formalin-fixed paraffin-embedded tissue sections of sentinel lymph nodes from patients with cutaneous melanoma, without macro-metastases were evaluated with this cocktail.

RESULTS

Melanoma micrometastases were easily detectable with the cocktail in 41 out of 188 slices (8/24 cases). The diagnostic accuracy amongst five pathologists did not show statistically significant difference. Out of 188 slices, 78 had adjacent sections immunostained individually with MART-1 and Melan-A during our previous study. Of these 78 slices, 21 were positive for melanoma micrometastases with MART-1 and Melan-A individually. However, the adjacent section of these slices immunostained with the cocktail detected metastases in four additional slices. Thus, MART-1 and Melan-A could not detect melanoma micrometastases individually in 16% (4/25) of slices positive with the cocktail. Benign capsular nevi were immunoreactive for the cocktail in 4.8% (9/188) slices. All 81 slices of negative test controls (sentinel lymph nodes of mammary carcinoma) were interpreted correctly as negative for melanoma micrometastases.

CONCLUSIONS

The melanoma cocktail facilitated easy interpretation of melanoma micrometastases in sentinel lymph nodes with high interobserver agreement. There was improvement in detection rate with the cocktail as compared to MART-1 and Melan-A individually. Furthermore, this approach facilitates cost savings.

Clinical impact of false-negative sentinel node biopsy in primary breast cancer

BACKGROUND

The aim was to assess the false-negative sentinel node biopsy rate in women with early breast cancer and its implications in patient treatment.

METHODS

Between January 1995 and March 2001, 328 consecutive patients with clinically lymph node-negative primary operable breast cancer underwent lymphatic mapping and sentinel node biopsy using a combination of preoperative lymphoscintigraphy and/or blue dye. All underwent immediate axillary dissection. The intraoperative success rate in sentinel node identification, false-negative rate, predictive value of negative sentinel node status and overall accuracy were assessed. The clinical features and primary tumour characteristics for each false-negative case were reviewed.

RESULTS

The sentinel node was identified in 285 (86.9 per cent) of 328 women. The false-negative rate was 7.9 per cent (eight of 101). Most members of the breast multidisciplinary team would have instituted adjuvant systemic therapy for six false-negative cases based on clinical features and primary tumour histology. In all, only two (0.7 per cent) of 285 women who had sentinel node biopsy may have had their management and survival prospects potentially jeopardized owing to a false-negative sentinel node.

CONCLUSION

The results of this study suggest that the clinical impact of a false-negative sentinel node is low.

Recommendations for sentinel lymph node processing in breast cancer

The status of the sentinel lymph node (SLN) has been shown to accurately reflect the presence or absence of metastases in the axilla in patients with breast cancer. This study was designed to determine the optimal protocol for SLN processing. A total of 173 SLNs from 96 breast cancer patients who had successful SLN localization and underwent completion axillary node dissection were identified. All SLNs were negative for metastases by initial routine histologic evaluation. The nodes were submitted in a total of 300 blocks. Each block was serially sectioned to produce 10 levels. Pan-cytokeratin stain was performed on levels 3 and 8. All other levels were stained with hematoxylin and eosin. Metastases were identified in 22 SLNs from 19 patients by examining all 10 levels. The first two hematoxylin and eosin- or the first cytokeratin-stained levels were positive for metastases in 21 (95.5%) of the 22 positive SLNs. Two additional hematoxylin and eosin-stained and one cytokeratin-stained levels of each SLN correctly identified the status of the node in 94 (97.9%) of 96 patients. Therefore, we recommend that after an initial hematoxylin and eosin-stained section, two additional hematoxylin and eosin-stained sections and one cytokeratin-stained section should be evaluated.

Micro-metastases in axillary lymph nodes: an increasing classification and treatment dilemma in breast cancer due to the introduction of the sentinel lymph node procedure

BACKGROUND

Sentinel lymph node (SN) biopsy will increasingly replace axillary lymph node dissection (ALND) for staging in breast cancer. For daily practice, examination of the SN by serial sectioning (SS) and/or immunohistochemistry (IHC) is being promoted. Use of these techniques may result into stage migration due to the increased detection of micro-metastases. The consequence may be overshooting of patients with adjuvant therapy, as the prognostic relevance of (small) micro-metastases and isolated tumor cells is unclear.

METHODS

The prognostic impact of micro-metastases is determined by reviewing ALND studies with a follow up of at least 5 years, including more than 100 patients, before the SN era. Furthermore, studies in which conventionally haematoxylin-eosin (H&E) negative SNs are investigated for occult metastases by SS and/or IHC are reviewed.

RESULTS

In only one of eight studies, occult metastases were an independent risk factor for reduced survival. The outcome is dependent on the size of the nodal metastasis. IHC and SS as used in the SN procedure indeed induce a shift from pNO to pN1a (according to TNM).

CONCLUSION

By the thorough pathologic examination of the SN, isolated tumor cells and micro-metastases are more frequently detected. We propose to classify small micro-metastases (<0.5 mm) in a separate pN1a(min) category (min for minimal) to prevent stage migration. As the prognostic relevance of isolated tumor cells and (small) micrometastases has not been proven, the value of adjuvant therapy can be questioned for patients with otherwise good prognostic factors.

What the clinician needs from the pathologist: evidence-based reporting in breast cancer

Histopathology has a vital role in determining breast cancer management and pathologists must be part of the clinical team. Carcinoma size, grade, and especially lymph node status remain the best available prognostic factors. Metastatic carcinoma in axillary nodes is more important than any other prognostic factor presently available. ER status is an important predictor of response to endocrine manipulation, but its independent prognostic significance, and that of micrometastatic disease, circulating carcinoma cells and other molecular factors, even well-studied ones such as HER2 status, are less clear. Pathology is the first clinical speciality to subject its practice to rigorous scientific analysis, and it has stood up well. However, workers without appropriate experience in Pathology or scientific design have created difficulties by undertaking poorly planned studies with ill-defined end-points, lacking appropriate quality control. New analytical techniques and therapeutic targets make it essential that we learn from past mistakes and integrate pathologists into the research teams pursing clinical trials and the assessment of new bio-markers. Without this, input resource will be wasted on false leads that could have been curtailed. Morphology alone will not be enough to select patients likely to benefit in trials of new therapies, but selection 'tests' must be appropriate. The confusion of tests for selection of patients to receive Herceptin shows what happens when this process fails. Much of the microarray data being put into data-bases has no quality control, and meta-analysis of this data will produce even more conflict than the clinical trials. This can be avoided, as the ability to standardise is available.