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

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

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

Determination of sentinel lymph node (SLN) status in primary breast cancer by prospective use of immunohistochemistry increases the rate of micrometastases and isolated tumour cells: Analysis of 174 patients after SLN biopsy

AIM

The objective of the present study was to evaluate the prospective use of immunohistochemistry (IHC) for histopathological diagnosis of sentinel lymph node(s) (SLN) in primary breast cancer using stage migration and non-SLN metastases as endpoints in relation to metastatic involvement.

METHOD

Serial sectioning and prospective use of IHC were applied to SLN examination in addition to routine haematoxylin-eosin staining in 174 consecutive patients with unifocal T1-T2 breast cancer included in a National Sentinel Node Study. Axillary lymph node dissection (ALND) was performed in all cases with macrometastases, micrometastases and isolated tumour cells (ITC).

RESULTS

The SLN was found in 173/174 patients and a metastatic foci was found in 50 patients including 28/50 with macrometastases, 16/50 with micrometastases and 6/50 with ITC. IHC detected 3/16 of the micrometastases and 4/6 of ITC. Stage migration from N0 to N1mi was encountered in 3/132 patients by use of IHC. Non-SLN metastases were noted in 15/28 of patients with macrometastases and in 3/16 of patients with micrometastases, whereas no patient with ITC had additional metastases (p=0.007).

CONCLUSION

The prospective use of IHC and serial sectioning for histopathological diagnosis of SLNs increased the detection rate of N1mi and ITC, but only 3/132 patients were stage-migrated by use of IHC. Patients with ITC did not have any risk of non-SLN metastases, supporting that ALND can safely be omitted in this group of patients.

Sentinel lymph node biopsy as the new standard of care in the surgical treatment for breast cancer

During the recent years, based on the results of validation studies, the sentinel lymph node biopsy has replaced routine axillary dissection as the new standard of care in early breast cancer. The technique represents a minimally invasive, highly accurate method for axillary staging, which could spare approximately 65-70% of patients unnecessary axillary dissection and its related morbidity. Several technical and clinical controversies have been raised during the development of this new technique; the authors review the most important issues, some questions have already been answered and others are still under debate. As far as the technical aspects are concerned, mapping techniques, appropriate surgical training, options for pathological examination of sentinel lymph nodes and the issue of nonaxillary sentinel lymph nodes are discussed. An update on clinical controversies demonstrates that factors such as large tumor size, palpable axillary nodes, multifocality and multicentricity, previous breast and axillary surgery, and pregnancy are no longer regarded as absolute contraindications for sentinel lymph node biopsy. Feasibility, accuracy and timing of sentinel lymph node biopsy in patients undergoing neoadjuvant chemotherapy remain unsolved issues, as well as the indication of the technique for some subgroups of in situ lesions. Finally, one of the most attractive open forums for debate will be discussed: whether or not completion of axillary dissection in the case of positive SLN is always required.

Prognostic significance of total number of nodes removed, negative nodes removed, and ratio of positive nodes to removed nodes in node positive breast carcinoma

BACKGROUND

This study was undertaken to investigate whether total number of nodes (pNtot) removed, negative nodes removed (pNneg), and ratio of positive nodes to total nodes removed (pNratio) are predictors of survival in node positive patients.

STUDY DESIGN

The records of 801 consecutive invasive breast cancer patients with T1-3 tumour and positive axillary lymph node who underwent modified radical mastectomy in our hospital were reviewed. pNtot and pNneg were categorized, and pNratio was computed. The influence of these probable prognostic factors on survival was investigated. Survival curves were generated by Kaplan-Meier method and log-rank test was used for comparisons. Multivariate analyses were performed by Cox proportional hazard model.

RESULTS

Median pNtot, and pNneg are 19 (range 5-54), and 13 (range 0-53), respectively. pNtot>15, and pNneg>15 were independently associated with reduced hazard ratios (HRs) of 0.62 (CI 0.48-0.79), and 0.68 (CI 0.52-0.89), respectively. The highest ratio (>0.25) of pNratio is associated with the highest hazard ratio for death (HR 3.8, CI 2.74-5.50) compared to the lowest ratio for death (<0.001).

CONCLUSIONS

pNtot, pNneg, and pNratio appear prognostic factors for survival in node positive breast cancers. Axillary lymph node dissection with more number of nodes removed (>15) or negative nodes (>15) are associated with increased survival.

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.

Differences in Sentinel Lymph Node Pathology Protocols Lead to Differences in Surgical Strategy in Breast Cancer Patients

BACKGROUND

Internationally, there is no consensus on the pathology protocol to be used to examine the sentinel lymph node (SN). At present, therefore, various hospitals use different SN pathology protocols of which the effect has not been fully elucidated. We hypothesized that differences between hospitals in SN pathology protocols affect subsequent surgical treatment strategies.

METHODS

Patients from four hospitals (A-D) were prospectively registered when they underwent an SN biopsy. In hospitals A, B, and C, three levels of the SN were examined pathologically, whereas in hospital D, at least seven additional levels were examined. In the absence of apparent metastases with hematoxylin and eosin examination, immunohistochemical examination was performed in all four hospitals.

RESULTS

In total, 541 eligible patients were included. In hospital D, more patients were diagnosed with a positive SN (P < .001) as compared with hospitals A, B, and C, mainly because of increased detection of isolated tumor cells. This led to more completion axillary lymph node dissections in hospital D (66.3% of patients (P < .0001), compared with 29.0% in hospitals A, B, and C combined). Positive non-SNs were detected in 13.9% of patients in hospital D, compared with 9.7% in hospitals A, B, and C (P = .70). That is, in 52.4% of patients in hospital D, a negative completion axillary lymph node dissection was performed, compared with 19.3% of patients in hospitals A, B, and C combined.

CONCLUSIONS

Differences in SN pathology protocols between hospitals do have a substantial effect on SN findings and subsequent surgical treatment strategies. Whether ultrastaging and, thus, additional surgery can offer better survival remains to be determined.

Pathologic Examination of the Sentinel Lymph Node: What Is the Best Method?

Sentinel lymph node biopsy (SLNB) has become an acceptable alternative to complete axillary dissection to determine whether breast cancer has spread to axillary lymph nodes. Yet the best method for pathologic examination of the sentinel lymph node (SLN) remains controversial. For years there has been speculation that micrometastases in axillary lymph nodes were clinically insignificant and thus lymph nodes did not require sectioning at close intervals. Yet essentially all studies, including a recent large prospective study, have found a significantly poorer prognosis associated even with metastases less than 2 mm in size-the most common definition of micrometastasis-suggesting that such small metastases cannot be safely overlooked. The use of immunohistochemistry (IHC) to detect keratin proteins will reveal metastatic breast carcinoma in about 18% of axillary lymph nodes that appear negative on routine stains. The preponderance of evidence to date suggests a significantly poorer prognosis in patients with such occult metastases, although data from large prospective studies are lacking. Molecular techniques such as polymerase chain reaction (PCR) offer even more sensitive methods for detecting occult metastasis in SLNs, although false positives are a particular problem in techniques that do not permit morphologic correlation, and for now they remain a research tool. Intraoperative examination of the SLN permits a completion axillary dissection to be performed during the same procedure if metastatic tumor is found; however, intraoperative techniques such as cytologic examination and frozen section lack sensitivity, and can result in loss of up to 50% of the SLN tissue. A proposal for optimal pathologic examination of the SLN is offered based on the above data.

Paradigm Shift of Staging and Treatment for Early Breast Cancer in the Sentinel Lymph Node Era

Lymph node status is the most reliable prognostic indicator for the clinical outcome of patients with most solid cancers. Because it is the first node draining the primary cancer, the sentinel lymph node (SLN) is most likely to harbor metastatic cancer cells. The tumor size of primary breast cancer is highly correlated with SLN metastasis. If the SLN is negative, the negative predictive value of the remaining nodal basin exceeds 95%. It appears that even using different techniques from different institutions, the successful rate to harvest the SLN is more than 95%. The false-negative rate is about 5-10% in most series. Breast cancer patients with early detection and a negative SLN have a significantly improved survival rate. The SLN data in breast cancer is so convincing that SLN information has been incorporated into the new American Joint Committee on Cancer (AJCC) classification of breast cancer. The therapeutic value of additional lymph node dissection after a positive SLN for breast cancer is still controversial. Follow-up data from breast cancer patients is somewhat limited, but available information shows that patients with negative SLNs fare much better. In summary, several important patterns of metastasis can be established based on the current SLN experience: 1) The earlier the breast cancer is found, the less the metastatic potential. 2) In most cases, breast cancer follows an orderly progression of metastasis to the SLN. 3) A small subgroup of patients may develop systemic dissemination without SLN involvement. Since metastatic cancer is usually incurable, it is important for oncologists to detect and resect an early breast cancer without delay. The challenge in the future will be to dissect these different patterns of metastasis based on molecular or genetic markers. Such information will be critical to select high-risk patients for adjuvant therapy.

Primary Breast Cancer Features Can Predict Additional Lymph Node Involvement in Patients with Sentinel Node Micrometastases

OBJECTIVE

The aim of this retrospective study was to identify biological features of primary breast cancer from which to predict the presence of further axillary involvement in patients bearing micrometastases in the sentinel lymph node (SLN).

METHODS

From a starting group of 690 patients, we isolated patients with micrometastases in the SLN. Those patients were classified according to the presence/absence of further metastases in nonsentinel lymph nodes (NSLNs). We examined primary tumor features to identify any relevant difference. Analysis of primary tumors evaluated histology, tumor size, lymphovascular invasion, mitotic index (Mib-1), estrogen and progesterone receptor status (ER/PR status), C-erb B-2 (HER-2/neu) expression and amplification, and p53 expression. Chi square analysis for statistical significance was applied.

RESULTS

Of the original 690 patients, 296 showed some kind of metastases in the SLN; 238 patients had gross metastases in the SLN. After axillary lymph node dissection (ALND), 102 patients (43%) had NSLNs with metastases, and 136 (57%) had negative axillary non-sentinel nodes. Another 58 patients harbored solitary micrometastases in the SLN. After ALND, 8 (14%) patients had further NSLN involvement, and 50 (86%) had negative axillary nodes.

CONCLUSIONS

Analysis of the primary breast lesion in patients with micrometastatic SLN and metastatic NSLNs revealed the presence of lymphovascular invasion, Mib-1 index > 10%, and tumor size > 2 cm. Patients without lymphovascular invasion, Mib-1 < 10% and T size < 2 cm could avoid further ALND.

Tumor-infiltrating CD4+ T lymphocytes in early breast cancer reflect lymph node involvement

BACKGROUND

The role of immune system in the pathogenesis and progression of breast cancer is a subject of controversy, and this stimulated us to investigate the association of the immunophenotype of tumor-infiltrating lymphocytes in early breast cancer with the spread of tumor cells to axillary lymph nodes.

METHODS

Tumor samples from 23 patients with early breast cancer from the Department of Gynecology and Obstetrics of Ribeirão Preto Medical School (USP) were obtained at the time of biopsy and submitted to an enzyme-digestion procedure for the extraction of tumor-infiltrating lymphocytes. The lymphocytes extracted were analyzed by dual-color flow cytometry with monoclonal antibodies in these combinations: CD3 FITC/CD19 PE, CD3 FITC/CD4 PE, CD3 FITC/CD8 PE, and CD16/56 PerCP, which are specific for immunophenotyping of T and B lymphocytes, helper and cytotoxic T lymphocytes, and natural killer (NK) cells. The mean percentage of these cells was used for comparing groups of patients with or without lymph node metastasis.

RESULTS

The mean value for T-lymphocyte infiltration was 24.72 +/- 17.37%; for B-lymphocyte infiltration, 4.22 +/- 6.27%; for NK-cell infiltration, 4.41 +/- 5.22%, and for CD4(+) and CD8(+) T-lymphocyte infiltration, 12.43 +/- 10.12% and 11.30 +/- 15.09%, respectively. Only mean values of T- and CD4(+) T-lymphocyte infiltration were higher in the group of patients with lymph node metastasis, while no differences were noted in the other lymphocyte subpopulations.

CONCLUSION

The association of tumor-infiltrating CD4(+) T lymphocytes with lymph node metastasis suggests a role for these cells in the spread of neoplasia to lymph nodes in patients with early breast cancer.

Micrometastases in Sentinel Lymph Node in a Multicentric Study: Predictive Factors of Nonsentinel Lymph Node Involvement—Groupe Des Chirurgiens De La Federation Des Centres De Lutte Contre Le Cancer

Purpose

To determine the rate of nonsentinel lymph node (NSN) involvement at axillary lymph node dissection (ALND) and predictive factors of this involvement following detection of micrometastasis in sentinel nodes (SN).

Methods

We analyzed 700 observations of SN micrometastases with additional ALND with the characteristics of the patients, tumors, and SN.

Results

Involvement of SN was diagnosed 388 times by serial sections (55.4%) with standard hemoxylin and eosin staining (HES) and 312 times solely on immunohistochemical analysis (IHC; 44.6%). The accurate size of the micrometastases was indicated in 488 cases: 301 larger than 0.2 mm (61.7%) and 187 ≤ 0.2 mm (38.3%). Ninety-four patients (13.4%) presented an NSN involvement with only one NSN involved in 62 cases (66%). Predictive factors of NSN involvement were in univariate analysis (pT stage [P < .000], menopausal status [P = .048], T stage [P = .006], grade [P = .013], lymphovascular invasion [LVI; P = .013], histologic tumor type [P = .017], and method of micrometastasis detection, by HES or IHC [P = .015]) and in multivariate analysis (pT stage ≤ or > 20 mm [odds ratio, 2.54], micrometastases detected by HES or IHC [odds ratio,1.734], presence or absence of LVI [odds ratio, 1.706]). Micrometastasis size ≤ or greater than 0.2 mm was not predictive.

Conclusion

This study confirms the value of serial sections and the vital role played by IHC in screening for small micrometastases. Omission of additional ALND may be envisaged with minimal risk for pT1a and pT1b tumors, and pT1a-b-c tumors corresponding to tubular, colloidal, or medullar cancers.

Mutation of the PIK3CA oncogene in human cancers

It is now well established that cancer is a genetic disease and that somatic mutations of oncogenes and tumour suppressor genes are the initiators of the carcinogenic process. The phosphatidylinositol 3-kinase signalling pathway has previously been implicated in tumorigenesis, and evidence over the past year suggests a pivotal role for the phosphatidylinositol 3-kinase catalytic subunit, PIK3CA, in human cancers. In this review, we analyse recent reports describing PIK3CA mutations in a variety of human malignancies, and discuss their possible implications for diagnosis and therapy.

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.

Meeting Highlights: International Expert Consensus on the Primary Therapy of Early Breast Cancer 2005

The ninth St Gallen (Switzerland) expert consensus meeting in January 2005 made a fundamental change in the algorithm for selection of adjuvant systemic therapy for early breast cancer. Rather than the earlier approach commencing with risk assessment, the Panel affirmed that the first consideration was endocrine responsiveness. Three categories were acknowledged: endocrine responsive, endocrine non-responsive and tumors of uncertain endocrine responsiveness. The three categories were further divided according to menopausal status. Only then did the Panel divide patients into low-, intermediate- and high-risk categories. It agreed that axillary lymph node involvement did not automatically define high risk. Intermediate risk included both node-negative disease (if some features of the primary tumor indicated elevated risk) and patients with one to three involved lymph nodes without additional high-risk features such as HER 2/neu gene overexpression. The Panel recommended that patients be offered chemotherapy for endocrine non-responsive disease; endocrine therapy as the primary therapy for endocrine responsive disease, adding chemotherapy for some intermediate- and all high-risk groups in this category; and both chemotherapy and endocrine therapy for all patients in the uncertain endocrine response category except those in the low-risk group.