Size of breast cancer metastases in axillary lymph nodes: clinical relevance of minimal lymph node involvement

Stage migration after introduction of sentinel lymph node dissection in breast cancer treatment in Denmark: a nationwide study

PURPOSE

To estimate the size and therapeutic consequences of stage migration after introduction of sentinel lymph node dissection (SLND) in breast cancer treatment in Denmark.

PATIENTS AND METHODS

We compared the distribution of lymph node metastases in breast cancer patients operated in 1993-1996 and 2005-2008; before and after introducing SLND. The study was based on data from the national Danish Breast Cancer Cooperative Group (DBCG) database.

RESULTS

We included 24,051 patients in the study; 10,231 patients from the first period and 13,820 from the second period. The proportion of patients having macrometastases was not significantly different in the two periods, whereas the proportion of patients with micrometastases increased from 5.1% to 9.0% (P<0.0001). However, this only resulted in an estimated change, from 7.8% to 8.8%, in the proportion of patients offered adjuvant systemic treatment due to positive nodal status as the only high-risk criterion, when using today's criteria for risk-allocation. In addition, we found that negative hormone receptor status was associated to negative nodal status when adjusted for confounders (odds ratios (OR) 0.83, P<0.0001).

CONCLUSION

Introduction of SLND in breast cancer treatment in Denmark has resulted in a stage migration on 4% due to identification of more micrometastases. However, this stage migration has only minor impact on patients offered adjuvant systemic treatment because nodal status today is less important in risk-allocation.

Prognostic value of lymph node micrometastases in breast cancer: a multicenter cohort study

Background

To evaluate the prognostic meaning of lymph node micrometastases in breast cancer patients.

Methods

Between January 2000 and January 2003, 1411 patients with a cT_1-2N₀ invasive breast carcinoma underwent surgery in 7 hospitals in the Netherlands. Sentinel lymph node biopsy was done in all patients. Based on lymph node status, patients were divided into 4 groups: _pN₀ (n = 922), _pN_1micro (n = 103), _pN_1a (n = 285), and _pN_≥1b (n = 101). Median follow-up was 6.4 years.

Results

At the end of follow-up, 1121 women were still alive (79.4%), 184 had died (13.0%), and 106 were lost to follow-up (7.5%). Breast cancer recurred in 244 patients: distant metastasis (n = 165), locoregional relapse (n = 83), and contralateral breast cancer (n = 44). Following adjustment for possible confounding characteristics and for adjuvant systemic treatment, overall survival (OS) remained comparable for _pN₀ and _pN_1micro and was significantly worse for _pN_1a and _pN_≥1b (hazard ratio [HR] 1.18; 95% confidence interval [95% CI] 0.58–2.39, HR 2.47; 95% CI 1.69–3.63, HR 4.36; 95% CI 2.70–7.04, respectively). Disease-free survival (DFS) was similar too in the _pN₀ and _pN_1micro group, and worse for _pN_1a and _pN_≥1b (HR 0.96; 95% CI 0.56–1.67 vs HR 1.64; 95% CI 1.19–2.27, HR 2.95; CI 1.98–4.42). The distant metastases rate also did not differ significantly between the _pN₀ and _pN_1micro group and was worse for _pN_1a and _pN_≥1b (HR 1.22; 95% CI 0.60–2.49, HR 2.26; 95% CI 1.49–3.40, HR 3.49; CI 2.12–5.77).

Conclusions

In breast cancer patients survival is not affected by the presence of micrometastatic lymph node involvement.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-010-1451-z) contains supplementary material, which is available to authorized users.

Micrometastatic disease and isolated tumor cells as a predictor for additional breast cancer axillary metastatic burden

BACKGROUND

Our study aims were to investigate breast cancer patients with micrometastases or isolated tumor cells (ITCs) in sentinel lymph nodes (SLNs) to determine the rate of non-SLN metastasis and axillary recurrences, and to compare actual non-SLN metastasis rates with those predicted by the Memorial Sloan-Kettering Cancer Center (MSKCC) nomogram.

METHODS

We identified 116 stage I to III breast cancer patients who underwent sentinel lymph node biopsy and had micrometastases or ITCs (<2-mm deposits). Patients underwent completion axillary lymph node dissection (ALND) (group 1) or had no further axillary surgery (group 2). P < 0.05 was considered statistically significant.

RESULTS

Of 116 patients with micrometastases or ITCs in SLNs, 55 (47%) underwent completion ALND (group 1), and 61 (53%) had no further axillary surgery (group 2). The rate of non-SLN metastases in group 1 patients was 9 (16%) of 55, which was significantly less than that predicted by the MSKCC nomogram (median 30%, P < 0.001). Patient age, race, tumor histology, tumor grade, estrogen receptor/Her-2neu status, and lymphovascular invasion did not differ significantly between group 1 patients with positive non-SLNs and those with negative non-SLNs (P > 0.05 for each), but patients with positive non-SLNs had larger tumors (P < 0.001). No patient in group 1 experienced an axillary recurrence, while only one patient (1.6%) in group 2 experienced axillary recurrence.

CONCLUSIONS

The actual rate of positive non-SLNs for breast cancer patients with SLN micrometastases or ITCs who underwent completion ALND was significantly less than that predicted by the MSKCC nomogram. The rate of axillary recurrence is negligible, regardless of the extent of axillary staging.

Breast cancer survival in relation to the metastatic tumor burden in axillary lymph nodes

PURPOSE

The aim of this study was to determine the prognostic significance of lymph node micrometastases in patients with breast cancer.

PATIENTS AND METHODS

Between September 2000 and January 2004, 3,369 patients with breast cancer were included in a prospective cohort. According to their lymph node status, they were classified in the following four groups: 2,383 were node negative, 107 had isolated tumor cells, 123 had micrometastases, and 756 had macrometastases. Median follow-up time was 52 months. Kaplan-Meier estimates and the multivariate Cox proportional hazard regression model were used to analyze survival.

RESULTS

Five-year cause-specific and event-free survival rates were lower for patients with micrometastases (pN1mi) than for node-negative (pN0) patients (94.1% v 96.9% and 79.6% v 87.1%, respectively; P = .020 and P = .032, respectively). There was no significant survival difference between node-negative patients and those with isolated tumor cells. The overall survival of pN1mi and pN0 patients did not differ.

CONCLUSION

This study demonstrates a worse prognosis for patients with micrometastases than for node-negative patients.

[Micrometastasis in the sentinel node and axillary lymph node macro-metastasis in breast cancer]

AIM

The study of the sentinel node has made it possible to obtain more comprehensive knowledge about the extent of axillary involvement in breast cancer. It has also decreased the surgical morbidity associated to the surgical examination of the axilla. The systematic use of immunohistochemical staining and molecular biology techniques improves the ability to detect the presence of micrometastasis or isolated tumor cells in a significant number of cases when this is the only sign of the lymph node extension of the disease. The possibility of avoiding complete axillary lymphadenectomy in those patients who are only affected by micrometastasis is proposed because of the low incidence of further involvement of the remaining lymph nodes.

MATERIAL AND METHOD

159 patients diagnosed of stage T1 or T2 breast cancer, in which the sentinel node had been identified by scintigraphy and intraoperative localization, were included in the study. Complete axillary lymphadenectomy was performed when micro- or macrometastases were found in the sentinel node, in order to determine the degree of axillary involvement.

RESULTS

A total of 40 patients (25%) showed infiltration of the sentinel node. This infiltration was only by micrometastasis in 17 of them (10.7%). Of these 17 patients, only 2 (11.8%) showed macro-metastasis in the lymphadenectomy. In the remaining subjects, the final staging reached after the sentinel node study was not modified.

CONCLUSION

It is possible to speculate that, in the future, axillary dissection can be avoided in those patients diagnosed of micrometastasis in the sentinel node, pending the conclusions of the on-going multicenter studies.

Breast cancer prognosis and occult lymph node metastases, isolated tumor cells, and micrometastases

BACKGROUND

The prognostic relevance of isolated tumor cells and micrometastases in lymph nodes from patients with breast cancer has become a major issue since the introduction of the sentinel lymph node procedure. We conducted a systematic review of this issue.

METHODS

Studies published from January 1, 1977, until August 11, 2008, were identified by use of MEDLINE, EMBASE, and the Cochrane Library. A total of 58 studies (total number of patients = 297,533) were included and divided into three categories according to the method for pathological assessment of the lymph nodes: cohort studies with single-section pathological examination of axillary lymph nodes (n = 285,638 patients), occult metastases studies with retrospective examination of negative lymph nodes by step sectioning and/or immunohistochemistry (n = 7740 patients), and sentinel lymph node biopsy studies with intensified work-up of the sentinel but not of the nonsentinel lymph nodes (n = 4155 patients). We used random-effects meta-analyses to calculate pooled estimates of the relative risks (RRs) of 5- and 10-year disease recurrence and death and the multivariably corrected pooled hazard ratio (HR) of overall survival of the cohort studies.

RESULTS

In the cohort studies, the presence (vs the absence) of metastases of 2 mm or less in diameter in axillary lymph nodes was associated with poorer overall survival (pooled HR of death = 1.44, 95% confidence interval [CI] = 1.29 to 1.62). In the occult metastases studies, the presence (vs the absence) of occult metastases was associated with poorer 5-year disease-free survival (pooled RR = 1.55, 95% CI = 1.32 to 1.82) and overall survival (pooled RR = 1.45, 95% CI = 1.11 to 1.88), although these endpoints were not consistently assessed in multivariable analyses. Sentinel lymph node biopsy studies were limited by small patient groups and short follow-up.

CONCLUSION

The presence (vs the absence) of metastases of 2 mm or less in diameter in axillary lymph nodes detected on single-section examination was associated with poorer disease-free and overall survival.

Axillary node staging by ultrasonography and fine-needle aspiration cytology in patients with breast cancer

Background

This study evaluated the role of axillary ultrasonography (AUS) and fine-needle aspiration cytology (FNAC) in preoperative staging of the axilla in patients with invasive breast cancer.

Methods

Between October 2006 and March 2009, 502 patients scheduled to undergo surgery for invasive breast cancer had preoperative AUS. All patients with suspicious nodes on ultrasonography underwent FNAC, and those with positive cytology proceeded directly to axillary node clearance. Patients with normal findings on AUS or negative cytology underwent sentinel node biopsy (SNB).

Results

A total of 137 (27·3 per cent) of 502 patients had axillary node metastases on final histology. Thirty-nine (28·5 per cent) node-positive patients were identified by AUS–FNAC and spared unnecessary SNB. AUS–FNAC had a sensitivity of 28·5 per cent and a specificity of 100 per cent for detecting axillary nodal metastases. AUS–FNAC findings were normal in all 15 patients with nodal micrometastases and in 11 patients with isolated tumour cells on histopathology. The sensitivity of AUS–FNAC had a positive correlation with invasive tumour size (odds ratio 1·03) and grade (odds ratio 2·80).

Conclusion

Preoperative AUS–FNAC avoided unnecessary SNB in 28·5 per cent of node-positive patients and in 7·8 per cent of patients overall.

Recent advances in the surgical care of breast cancer patients

A tremendous improvement in every aspect of breast cancer management has occurred in the last two decades. Surgeons, once solely interested in the extipartion of the primary tumor, are now faced with the need to incorporate a great deal of information, and to manage increasingly complex tasks.

As a comprehensive assessment of all aspects of breast cancer care is beyond the scope of the present paper, the current review will point out some of these innovations, evidence some controversies, and stress the need for the surgeon to specialize in the various aspects of treatment and to be integrated into the multisciplinary breast unit team.

Circulating endothelial cells and circulating progenitor cells in breast cancer: relationship to endothelial damage/dysfunction/apoptosis, clinicopathologic factors, and the Nottingham Prognostic Index

BACKGROUND AND METHODS

Abnormal circulating endothelial cell (CEC) and circulating progenitor cell (CPC) numbers are present in cancer, but their relationship with angiogenesis, apoptosis, vascular biology, and prognosis is unclear. We prospectively studied 160 patients with breast cancer and 63 age-matched controls free of breast cancer, measuring CECs (CD45(-)/CD146(+)/CD34(+)) and CPCs (CD45(-)/CD133(+)/CD34(+)) by flow cytometry and plasma markers of endothelial damage/dysfunction (von Willebrand factor), apoptosis (Fas/Fas-L) and angiogenesis (vascular endothelial growth factor [VEGF], angiogenin) by ELISA. These were compared with clinicopathophysiologic features and the Nottingham Prognostic Index (NPI). An additional blood sample was taken 6 to 8 weeks after surgery from 15 women to test the effect of tumor removal.

RESULTS

CECs were significantly higher in the NPI poor prognostic group compared with moderate and good prognostic groups, and the cancer-free controls, whereas CPCs were lower in the poor prognosis group (both P < .05). Levels of von Willebrand factor, VEGF, angiogenin, and Fas-L (but not soluble Fas) were abnormal in breast cancer compared with controls (P < .05), with no relationship to prognosis groups. VEGF (P = .04) and angiogenin (P = .001) were markedly different after surgery. In multivariate analysis, vascular invasion (P < .05) and tumor size (P < .001) were independently associated with CECs. CPCs did not significantly associate with NPI in a linear regression model; age (P < .05) was a negative predictor, whereas Her-2 status (P < .05) positively predicted CPCs. After adjustment, no variable independently predicted CPC levels.

CONCLUSIONS

CECs and CPCs demonstrate a strong relationship with NPI groups, but only CECs positively predict higher NPI scores and correlate with tumor invasiveness and size, possibly reflecting total tumor vascular volume.

Axillary lymph node dissection for sentinel lymph node micrometastases may be safely omitted in early-stage breast cancer patients: long-term outcomes of a prospective study

OBJECTIVES

To evaluate the long-term disease-free and overall survival of patients with sentinel lymph node (SLN) micrometastases, in whom a completion axillary lymph node dissection (ALND) was systematically omitted.

BACKGROUND

The use of step sectioning and immunohistochemistry for SLN analysis results in a more accurate histopathologic examination and a higher detection rate of micrometastases. However, the clinical relevance and therapeutic implications of SLN micrometastases remain a matter of debate.

METHODS

In this prospective study, 236 SLN biopsies were performed in 234 consecutive early-stage breast cancer patients (T1, T2 <or= 3 cm, cN0 M0) between 1998 and 2002. The SLN were examined by step sectioning and stained with hematoxylin and eosin and immunohistochemistry. None of the patients with negative SLN or SLN micrometastases (International Union Against Cancer classification, >.2 mm to <or=2 mm) underwent a completion ALND or radiation to the axilla. Long-term overall and disease-free survivals were compared between patients with negative SLN and those with SLN micrometastases by log rank tests.

RESULTS

The SLN was negative in 55% of patients (123 of 224). SLN micrometastases were detected in 27 patients (27 of 224, 12%). After a median follow-up of 77 months (range, 24-106 months), neither locoregional recurrences nor distant metastases occurred in any of the 27 patients with SLN micrometastases. There were no statistically significant differences for overall (P = .656), locoregional (P = .174), and axillary and distant disease-free survival (P = .15) between patients with negative SLN and SLN micrometastases.

CONCLUSIONS

This analysis of unselected patients provides evidence that a completion level I and II ALND may be safely omitted in early-stage breast cancer patients with SLN micrometastases.

Impact of micrometastases in the sentinel node of patients with invasive breast cancer

PURPOSE

Lymph node metastases are the most significant prognostic indicator for patients with breast cancer. Sentinel node biopsy (SNB) has led to an increase in the detection of micrometastases in the sentinel node (SN). This prospective study was designed to determine the survival impact of micrometastases in SNs of patients with invasive breast cancer. This study is based on the new sixth edition of the American Joint Committee on Cancer (AJCC) staging criteria.

PATIENTS AND METHODS

Between January 1, 1992 and April 30, 1999, 790 patients entered this prospective study at the John Wayne Cancer Institute. The SN was examined first by hematoxylin and eosin (HE), and if the SN was negative with HE, then immunohistochemical staining was performed. The patients were then divided into four groups based on AJCC nodal staging: pN0(i-), no evidence of tumor (n = 486); pN0(i+), tumor deposit < or = 0.2 mm (n = 84); pN1mi, tumor deposit more than 0.2 mm but < or = 2 mm (n = 54), and pN1, tumor deposit more than 2 mm (n = 166). Disease-free survival (DFS) and overall survival (OS) were estimated using the Kaplan-Meier method. The log-rank test was used to determine differences in DFS and OS of patients from different groups.

RESULTS

At a median follow-up of 72.5 months, the size of SN metastases was a significant predictor of DFS and OS.

CONCLUSION

Patients with micrometastatic tumor deposits, pN0(i+) or pN1mi, do not seem to have a worse 8-year DFS or OS compared with SN-negative patients. As expected, there was a significant decrease in 8-year DFS and OS in patients with pN1 disease in the SN.

Micrometastases or isolated tumor cells and the outcome of breast cancer

BACKGROUND

The association of isolated tumor cells and micrometastases in regional lymph nodes with the clinical outcome of breast cancer is unclear.

METHODS

We identified all patients in The Netherlands who underwent a sentinel-node biopsy for breast cancer before 2006 and had breast cancer with favorable primary-tumor characteristics and isolated tumor cells or micrometastases in the regional lymph nodes. Patients with node-negative disease were randomly selected from the years 2000 and 2001. The primary end point was disease-free survival.

RESULTS

We identified 856 patients with node-negative disease who had not received systemic adjuvant therapy (the node-negative, no-adjuvant-therapy cohort), 856 patients with isolated tumor cells or micrometastases who had not received systemic adjuvant therapy (the node-positive, no-adjuvant-therapy cohort), and 995 patients with isolated tumor cells or micrometastases who had received such treatment (the node-positive, adjuvant-therapy cohort). The median follow-up was 5.1 years. The adjusted hazard ratio for disease events among patients with isolated tumor cells who did not receive systemic therapy, as compared with women with node-negative disease, was 1.50 (95% confidence interval [CI], 1.15 to 1.94); among patients with micrometastases, the adjusted hazard ratio was 1.56 (95% CI, 1.15 to 2.13). Among patients with isolated tumor cells or micrometastases, the adjusted hazard ratio was 0.57 (95% CI, 0.45 to 0.73) in the node-positive, adjuvant-therapy cohort, as compared with the node-positive, no-adjuvant-therapy cohort.

CONCLUSIONS

Isolated tumor cells or micrometastases in regional lymph nodes were associated with a reduced 5-year rate of disease-free survival among women with favorable early-stage breast cancer who did not receive adjuvant therapy. In patients with isolated tumor cells or micrometastases who received adjuvant therapy, disease-free survival was improved.

Minimal axillary lymph node involvement in breast cancer has different prognostic implications according to the staging procedure

It is still controversial whether the identification of micrometastases and isolated tumor cells in the axillary lymph nodes of patients with breast cancer has any prognostic value. We evaluated the prognostic role of isolated tumor cells and micrometastases in the axillary lymph nodes in 3,158 consecutive patients pT1-2 pN0-N1mi (with a single involved lymph node) and M0, referred to the Division of Medical Oncology after surgery performed at the European Institute of Oncology from April 1997 to December 2002. Median follow-up was 6.3 years (range 0.1-11 years). Sentinel lymph node biopsy (SLNB) and axillary lymph node dissection (ALND) were performed in 2,087 and 1,071 patients, respectively. A worse metastasis-free survival was observed for patients with micrometastatic disease compared to node-negative patients, if staged with ALND (log-rank P < .0001; HR: 3.17; 95% CI 1.72-5.83 at multivariate analysis), but not for patients who underwent SLNB (log-rank P = 0.36). The presence of a single micrometastatic lymph node is associated with a higher risk of distant recurrence as compared to node-negative disease only for patients undergoing ALND for staging purposes. Treatment recommendations for systemic therapy should not take into account the presence of a single micrometastatic lymph node identified during complete serial sectioning of sentinel node(s).

Estrogen receptor immunohistochemistry for confirmation of sentinel lymph node metastasis in cases with equivocal cytokeratin positivity

Differentiation of true metastases from cytokeratin (CK)-positive nonepithelial cells by immunohistochemistry occasionally may be difficult in the evaluation of sentinel lymph nodes (SLNs) for occult breast carcinoma metastases. In this study, we evaluated estrogen receptor (ER) immunostaining superimposed on CK as a method for the confirmation of metastasis when CK immunostaining alone was equivocal. We performed sequential ER staining on previously CK-stained slides on 15 axillary SLNs from breast cancer patients: 5 SLNs with known metastatic carcinoma (positive controls), 6 known negative SLNs (negative controls), and 4 test cases (3 SLNs in which CK-positive cells were equivocal for malignancy and 1 SLN in which metastasis was obvious, but contained focal weakly CK-positive signet ring cells). The primary tumor in all cases expressed ER in >50% of cells. Only 3 of 5 positive controls showed metastatic cells with dual CK/ER staining. CK-positive reticulum cells in all negative controls were ER negative. Three test cases showed dual CK/ER staining in the equivocal cells. The case with signet ring cells showed strong ER staining in the nonsignet ring cells and weaker staining in the signet ring cells. We conclude that dual CK/ER staining can be useful in SLNs when CK staining alone is equivocal, particularly when the primary tumor is known to have high expression of ER. Although dual ER/CK positivity helps to confirm metastasis, negative ER staining does not exclude metastatic disease.

[Sentinel node biopsy in breast cancer: pathological analysis and interpretation]

This overview examines how the introduction of sentinel lymph node biopsy (SLNB) has changed the pathological staging of breast cancer. The more intensive analysis of the sentinel lymph nodes (gross slicing, step sections, immunohistological or molecular analysis) has lead to stage shifting in breast cancer. Regarding the rate of up-staging by positive results of SLNB, there are significant differences between institutes, some method-related, some related to the interpretation of results. Methodological differences should be reduced by means of reliable guidelines with the goal of systematically identifying metastases of a particular size (a macrometastasis over 2 mm being the minimum criterion). The next review of the TNM classification should result in a reduction in interobserver variability as a result of better definitions of staging categories for isolated tumor cells and micrometastases. In addition, a staging category is expected for metastases which have been identified by calibrated quantitative molecular tests only and which are larger than isolated tumors. Even in settings where nodal staging by SLNB is based on molecular tests at least a proportion of the lymph node should be investigated histologically.

Effects of humoral immunity and calreticulin overexpression on postoperative course in breast cancer

The aim was to investigate whether the humoral immunity and overexpression of calreticulin in tumor tissue determined before surgery, correlate with incidence of metastases in breast cancer patients within two years after operation. Before operation, their humoral immunity and overexpression of caleticulin and Her-2/neu in tumor tissue were analyzed by immunohystochemistry. In 23 patients with metastases in regionally lymph nodes, seven had Her-2/neu overexpression. Among those seven patients, three developed distant metastasis (two women one year and in one woman two years after surgery) and all of them showed the presence of stromal IgG immunoreactivity and overexpression of calreticulin in their tumors tissue. Preliminary data showed that serum IgG immunoreactivity to tumor stroma in combination with overexpression of calreticulin in tumor cells correlate with postoperative appearance of metastases, particularly in the group of patients with Her-2/neu overexpressed tumors and metastases in axillary lymph nodes.

The number of positive nodes and the ratio of positive to excised nodes are significant predictors of survival in women with micrometastatic node-positive breast cancer

BACKGROUND

To evaluate the prognostic impact of the number of positive nodes and the lymph node ratio (LNR) of positive to excised nodes on survival in women diagnosed with nodal micrometastatic breast cancer before the era of widespread sentinel lymph node biopsy.

METHODS

Subjects were 62,551 women identified by the Surveillance Epidemiology and End Results database, diagnosed with pT1-2pN0-1 breast cancer between 1988 and 1997. Kaplan-Meier breast cancer-specific survival (BCSS) and overall survival (OS) were compared between three cohorts: node-negative (pN0, n=57,980) nodal micrometastasis all <or=2mm (pNmic, N=1818), and macroscopic nodal metastasis >2mm but <2 cm (pNmac, n=2753). Nodal subgroups were examined by the number of positive nodes (1-3 versus >or= 4) and the LNR (<or=0.25 versus >0.25).

RESULTS

Median follow-up was 7.3 yr. Ten-year BCSS and OS in pNmic breast cancer were significantly lower compared to pN0 disease (BCSS 82.3% versus 91.9%, p<0.001 and OS 68.1% versus 75.7%, p<0.001). BCSS and OS with pNmic disease progressively declined with increasing number of positive nodes and increasing LNR. OS with pNmic was similar to pNmac disease when matched by the number of positive nodes and by the LNR. Both pN-based and LNR-based classifications were significantly prognostic of BCSS and OS on Cox regression multivariate analysis.

CONCLUSION

Nodal micrometastasis is associated with poorer survival compared to pN0 disease. Mortality hazards with nodal micrometastasis increased with increasing number of positive nodes and increasing LNR. The number of positive nodes and the LNR should be considered in risk estimates for patients with nodal micrometastatic breast cancer.

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.

Minimal disease in sentinel nodes

Isolated tumor cells and micrometastases represent low-volume or minimal disease in the regional lymph nodes of breast cancer patients as compared to macrometastases. Sentinel lymph node biopsy is a functional selection and removal of the most likely site of regional metastasis, and gives pathologists the opportunity to concentrate detection techniques on a limited number of lymph nodes. Consequently, more lesions belonging in the two mentioned staging categories are discovered in sentinel lymph nodes. Despite some publications contradicting stochastic models of breast cancer, micrometastases seem to reflect a prognosis intermediate between the node-negative and macrometastatic nodal status, and they also reflect a risk of non-sentinel node involvement slightly higher than that associated with a node-negative status. Data are more contradictory as concerns isolated tumor cells. This minireview summarizes the definitions, their inconsistencies, pathological protocols aiming at the detection of minimal nodal disease, the prognostic impact and non-sentinel node involvement related risk of such nodal lesions, and their therapeutic consequences.

The clinical significance of sentinel lymph node micrometastasis in breast cancer

INTRODUCTION

The advent of sentinel lymph node biopsy (SLNB) and improvements in histopathological and molecular analysis have increased the rate at which micrometastases (MM) are identified. However, their significance has been the subject of much debate. In this article we review the literature concerning axillary lymph node (ALN) MM, with particular reference to SLNB. The controversies regarding histopathological assessment, clinical relevance and management implications are discussed.

METHODS

Literature review facilitated by Medline and PubMed databases.

RESULTS

Published studies have reported divergent results regarding the significance and implications of ALN MM in general and sentinel lymph node (SLN) MM in particular. Some studies demonstrate no associations, whilst others have found these to be indicators of poor prognosis, associated with non-SLN involvement, in addition to local and distant failure. Absolute consensus regarding the optimal analytical technique for SLNs has yet to be reached, particularly concerning immunohistochemical (IHC) techniques targeting cytokeratins and the utility of contemporary molecular analysis.

CONCLUSION

SLN MM are likely to represent an incremental detriment to prognosis and increased risk of non-SLN involvement, despite only modest up-staging within current classification systems. In the absence of level-1 guidance concerning the management of women with SLN MM, each case requires discussion with regard to other tumour and patient related factors in the context of the multidisciplinary team. Randomized studies are required to evaluate the prognostic significance and optimal management of each category of tumour burden within the SLN. The identification of MM remains highly dependent on the analytical technique employed and there exists potential for stage migration and impact on management decisions.

Nodal Stage Classification for Breast Carcinoma: Improving Interobserver Reproducibility Through Standardized Histologic Criteria and Image-Based Training

Purpose

Reliable pathologic stage classification of axillary lymph nodes is an important determinant of prognosis and therapeutic decision making for patients with invasive breast cancer. Pathologists' distinction between micrometastasis (pN1mi) and isolated tumor cells [ITC; pN0(i+)] is variable using the American Joint Committee on Cancer (AJCC) Staging Manual (Sixth Edition). We sought to determine whether a set of clearly defined histologic criteria could lead to reproducible nodal classification by pathologists.

Patients and Methods

Digital images of sentinel lymph node biopsies from 56 patients with small-volume nodal metastases were examined by six experienced breast pathologists (MDs), first as a pre-test, and again as a post-test after studying a training program that outlined and illustrated the classification criteria.

Results

Post-test results, after study of the training program, were significantly improved. Compared with the reference MD, agreement improved from 76.2% (pre-test κ = 0.575; standard deviation [SD], 0.25) to 97.3% (post-test κ = 0.947; SD, 0.049). Multirater analysis of agreement among the six MDs improved from 71.5% (pre-test κ = 0.487; ASE, 0.039) to 95.7% (post-test κ = 0.915; ASE, 0.037). Agreement on lobular carcinoma metastasis classification improved from 55% (23 of 42; pre-test) to 100% (42 of 42; post-test) (P < .001), and agreement on ITC classification in nodal parenchyma improved from 67.6% (69 of 102; pre-test) to 98.0% (100 of 102; post-test; P < .001).

Conclusion

Application of current definitions for classification of small-volume nodal metastases are inconsistent, leading to variable classification of ITC and micrometastases. Reproducibility of pathologic nodal stage classification is achievable through study of a training set to clarify the AJCC criteria.

Axillary lymph node micrometastases in invasive breast cancer: national figures on incidence and overall survival

The purpose of this study was to estimate the incidence and prognostic value of axillary lymph node micrometastases (Nmic) of 2 mm or less in breast carcinomas. Results are based on data from the Danish Breast Cancer Cooperative Group (DBCG). The study was carried out as a nationwide, population-based trial with a study series consisting of 6,959 women under 75 years of age registered in the national DBCG data base from 1 January 1990 to 31 October 1994. All patients had contracted operable primary breast carcinoma, stage I-III, classified according to the TNM system as T1-T3, N0-N1, M0. Women with four or more metastatic axillary lymph nodes were excluded. All patients were treated systematically according to approved national guidelines and treatment protocols. Metastases were recognized microscopically on haematoxylin and eosin-stained sections. In case of doubt immunohistochemical staining for cytokeratin was performed. There was no serial sectioning. Micrometastases were tumour deposits of 2 mm or smaller, and accordingly included deposits of 0.2 mm and smaller. With a median observation time of 10 years and 2 months, women with Nmic (N=427) experienced a significantly worse overall survival (OS) compared with node-negative (Nneg) women (N=4,767) (relative risk (RR)=1.20, 95% CI: 1.01-1.43), irrespective of menopausal status. Women with macrometastases (Nmac) (N=1,765) had significantly worse final outcome than women with Nmic (RR=1.54, 95% CI: 1.29-1.85), irrespective of menopausal status. Multivariate analysis adjusted for patient-, histopathologic-, and loco-regional therapeutic variables showed that cases with Nmic had a significantly higher risk of death relative to Nneg cases (adjusted RR=1.49, 95% CI: 1.18-1.90). Interaction analysis showed that the number of nodes examined had a significant impact on adjusted relative risk of death according to axillary status. Furthermore, the number of nodes involved significantly influenced adjusted risk of death in the Nmic compared to the Nmac series. In conclusion, the results of the present study revealed worse final outcome in women with Nmic compared with Nneg, where all Nmic cases received adjuvant systemic treatment. Interaction analysis showed that the number of retrieved axillary nodes and the number of affected nodes had a different influence on survival related to axillary status. The different risk pattern in Nmic vs Nmac patients indicates that Nmic cases do not show the traditional risk pattern as revealed by the Nmac cases, in which increasing number of positive nodes is associated with an orderly increasing adjusted RR.

Detection of micrometastases in the sentinel lymph nodes of patients with endometrial cancer

OBJECTIVE

We investigated the utility of sentinel lymph node (SLN) mapping for the detection of endometrial carcinoma micrometastases. We reevaluated the accuracy of our SLN detection procedure, this time combining step-serial section with cytokeratin immunostaining.

PATIENTS AND METHODS

Between March 2002 and March 2005, consecutive patients undergoing laparotomy (total abdominal hysterectomy, bilateral salpingo-oophorectomy, total pelvic lymphadenectomy and para-aortic lymphadenectomy to the level of renal veins) with SLN biopsy for endometrial cancer at Tohoku University Hospital were enrolled in this study. Excluded were patients in whom lymph node metastases were detected by routine histological examination or those without detectable SLNs. All surgically removed lymph nodes, including SLNs, were examined histopathologically by immunohistochemistry staining with an anti-cytokeratin antibody (AE1/AE3) combined with step-serial sectioning at 200-500 microm intervals.

RESULTS

Four of seventy-four SLNs (5%) obtained from 20 patients had micrometastases or isolated tumor cells (ITC). In contrast, only 4 of the 1350 non-SLNs obtained from 20 patients (0.3%) had detectable micrometastases. The micrometastases were detected in the external iliac basin (two cases) and in the para-aortic area (two cases). The isolated tumor cell was detected in the external iliac basin (one case).

CONCLUSION

SLNs detected by our method had micrometastases more frequently than did non-SLNs. Easy detection of micrometastases by immunostaining is only possible with step-serial sectioning of the SLNs.