Detection and Significance of Occult Axillary Metastatic Disease in Breast Cancer Patients

Dual-modal computer-assisted evaluation of axillary lymph node metastasis in breast cancer patients on both real-time elastography and B-mode ultrasound

PURPOSE

To propose a computer-assisted method for quantifying the hardness of an axillary lymph node on real-time elastography (RTE) and its morphology on B-mode ultrasound; and to combine the dual-modal features for differentiation of metastatic and benign axillary lymph nodes in breast cancer patients.

MATERIALS AND METHODS

A total of 161 axillary lymph nodes (benign, n=69; metastatic, n=92) from 158 patients with breast cancer were examined with both B-mode ultrasound and RTE. With computer assistance, five morphological features describing the hilum, size, shape, and echogenic uniformity of a lymph node were extracted from B-mode, and three hardness features were extracted from RTE. Single-modal and dual-modal features were used to classify benign and metastatic nodes with two computerized classification approaches, i.e., a scoring approach and a support vector machine (SVM) approach. The computerized approaches were also compared with a visual evaluation approach.

RESULTS

All features exhibited significant differences between benign and metastatic nodes (p<0.001), with the highest area under the receiver operating characteristic curve (AUC) of 0.803 and the highest accuracy (ACC) of 75.2% for a single feature. The SVM on dual-modal features achieved the largest AUC (0.895) and ACC (85.7%) among all methods, exceeding the scoring (AUC=0.881; ACC=83.6%) and the visual evaluation methods (AUC=0.830; ACC=84.5%). With the leave-one-out cross validation, the SVM on dual-modal features still obtained an ACC as high as 84.5%.

CONCLUSION

Dual-modal features can be extracted from RTE and B-mode ultrasound with computer assistance, which are valuable for discrimination between benign and metastatic lymph nodes. The SVM on dual-modal features outperforms the scoring and visual evaluation methods, as well as all methods using single-modal features. The computer-assisted dual-modal evaluation of lymph nodes could be potentially used in daily clinical practice for assessing axillary metastasis in breast cancer patients.

Selective or routine axillary disease staging for patients with clinically lymph node–negative breast cancer?

BACKGROUND

Although sentinel lymph node biopsy (SLNB) has become the standard for patients with clinically lymph node-negative breast cancer, less than one third of patients who undergo SLNB will have lymph node metastases. Therefore, we hypothesized that a subset of patients in whom SLNB can be avoided can be identified before operation.

METHODS

We prospectively studied 220 patients with early stage breast cancer who underwent SLNB. We analyzed primary tumor features, biologic markers, and demographic data.

RESULTS

Overall, 31% of the patients had lymph node metastases. Although patients with lymph node metastases had larger neoplasms than patients who were lymph node negative (mean, 2.3 +/- 0.1 cm versus 1.5 +/- 0.1 cm; P < .0001), 10% of patients with T1a tumors, 19% of patients with T1b tumors, and 30% of patients with T1c tumors had lymph node metastases. Palpable tumors were lymph node positive in 41% of patients versus 17% for nonpalpable tumors (P = .0001). Lymph node metastases were seen in 71% of patients with tumor angio or lymphatic invasion versus 17% of patients without (P < .0001). Seventy-five percent of patients with an increased preoperative serum CA 27.29 had lymph node metastases, and the mean levels were greater among patients who were lymph node positive (27 U/ml +/- 2 versus 20 +/- 1; P = .0002). There was no significant association between any other demographic, histologic, or molecular feature that was investigated and lymph node metastases.

CONCLUSION

We did not identify histologic, demographic, or molecular variables that can exclude the risk of associated lymphatic metastases reliably. Furthermore, not all predictive factors are known before the operation (eg, whether the tumor is T1a or T1b). Therefore, we recommend that SLNB be performed in all patients with clinically lymph node-negative invasive breast cancer.

Biological Significance of Occult Micrometastases in Histologically Negative Axillary Lymph Nodes in Breast Cancer Patients Using the Recent American Joint Committee on Cancer Breast Cancer Staging System

The biological significance of occult metastases in axillary lymph nodes of breast cancer patients is controversial. The purpose of the study was to determine the prognostic significance of occult micrometastases using the current American Joint Committee on Cancer (AJCC) staging system in a cohort of women with node-negative breast cancer, of whom 5% received adjuvant systemic therapy and who all had long-term follow-up. We studied a cohort of 214 consecutive histologically node-negative breast cancer patients with a median follow-up of 8 years. Blocks of the axillary lymph nodes were assessed for occult micrometastases by examination of an additional hematoxylin-eosin-stained slide and by immunohistochemical staining using an antibody to low molecular weight keratin. Occult metastases were classified according to the sixth edition of the AJCC cancer staging manual. We examined the prognostic effects of occult micrometastases and other clinicopathologic features on recurrence outside the breast with disease-free interval (DFI) and survival from breast cancer with disease-specific survival (DSS). Cytokeratin-positive tumor cells were identified in the lymph nodes in 29 of 214 cases (14%). Two cases had isolated tumor cells and no cluster larger than 0.2 mm [pN0(i+)], whereas 27 of 214 (13%) had micrometastases (larger than 0.2 mm and <or=2.0 mm] (pN1mi). None of the cases had macrometastases. With median 8 years follow-up, occult micrometastases were not significantly associated with any of the clinicopathologic features. In addition, occult micrometastases were not significantly associated with DFI or DSS and thus were not included in the multivariate analysis. On multivariate analysis, lymphovascular invasion was significantly associated with DFI (p < 0.001) and DSS (p = 0.02), whereas percentage S-phase was significantly associated with DSS (p = 0.02). This study, in which 95% of patients did not receive adjuvant systemic therapy, suggests that breast cancer patients with occult micrometastases in axillary lymph nodes have a similar prognosis to those with no micrometastases. This information is important with regard to the practice of sentinel node biopsy and subsequent axillary node dissection and to the decision to administer adjuvant therapy based on detection of micrometastases in lymph nodes.

A rapid, fully automated, molecular-based assay accurately analyzes sentinel lymph nodes for the presence of metastatic breast cancer

OBJECTIVE

To develop a fully automated, rapid, molecular-based assay that accurately and objectively evaluates sentinel lymph nodes (SLN) from breast cancer patients.

SUMMARY BACKGROUND DATA

Intraoperative analysis for the presence of metastatic cancer in SLNs from breast cancer patients lacks sensitivity. Even with immunohistochemical staining (IHC) and time-consuming review, alarming discordance in the interpretation of SLN has been observed.

METHOD

A total of 43 potential markers were evaluated for the ability to accurately characterize lymph node specimens from breast cancer patients as compared with complete histologic analysis including IHC. Selected markers then underwent external validation on 90 independent SLN specimens using rapid, multiplex quantitative reverse transcription-polymerase chain reaction (QRT-PCR) assays. Finally, 18 SLNs were analyzed using a completely automated RNA isolation, reverse transcription, and quantitative PCR instrument (GeneXpert).

RESULTS

: Following analysis of potential markers, promising markers were evaluated to establish relative level of expression cutoff values that maximized classification accuracy. A validation set of 90 SLNs from breast cancer patients was prospectively characterized using 4 markers individually or in combinations, and the results compared with histologic analysis. A 2-marker assay was found to be 97.8% accurate (94% sensitive, 100% specific) compared with histologic analysis. The fully automated GeneXpert instrument produced comparable and reproducible results in less than 35 minutes.

CONCLUSIONS

A rapid, fully automated QRT-PCR assay definitively characterizes breast cancer SLN with accuracy equal to conventional pathology. This approach is superior to intraoperative SLN analysis and can provide standardized, objective results to assist in pathologic diagnosis.

The reliability and accuracy of intraoperative imprint cytology of sentinel lymph nodes in breast cancer

OBJECTIVE

Sentinel lymph node (SLN) biopsy is a new component of the surgical treatment of breast cancer that accurately predicts axillary status. In this study the authors evaluated the accuracy of intraoperative imprint cytology (IC) in comparison with definitive histologic evaluation of SLN in breast cancer patients.

METHODS

A total 413 women with breast carcinoma and clinically negative axillary nodes underwent breast surgery and SLN biopsy. Mapping of SLN involved injection of (99m)Technecium labelled human albumin nanocolloid particles and Patent Blue dye. At the Department of Pathology, SLNs were bisected along its major axis. Both halves were imprinted 2-4 times on the slides and immediate staining with Hemacolor (Merck Germany) was performed for intraoperative examination. Imprint node negative women underwent no further surgery, while node positive women proceeded to full axillary clearance. Histological analysis of the SLN involved serial sectioning of the whole node with H&E and immunostaining for cytokeratin.

RESULTS

Definitive histology revealed metastases (pN+) in 159/413 patients (38.5%): 69 (16.7%) macro metastases, 57 (13.8%) micro metastases, and 33 (8%) women with only isolated IHC positive cells or positive cell groups smaller than 0.2 mm (pNO sn+). The other 254 women had negative SLN biopsy. Imprint cytology detected 54/69 macro metastases, and 4/57 micro metastases. In the group with negative SLN (254), 2 cases were ''false positives''.

CONCLUSIONS

Imprint of SLN biopsy can identify a negative axilla with high accuracy (specificity 99.2%). Overall sensitivity is only 36.5%, but macrometastases are detected in 77% which is important for performing ALDN in one session with operation of primary tumour.

[Molecular alterations in breast cancer: clinical implications and new analytical tools]

PURPOSE

Breast cancer is a complex and heterogeneous disease resulting from various molecular alterations, the identification of which should have profound impact on the management of patients.

CURRENT KNOWLEDGE AND KEY POINTS

The discovery of germline mutations within breast cancer susceptibility genes, such as BRCA1 and BRCA2, which are associated with a major risk of breast cancer during lifetime, has improved the assessment of the individual risk toward the disease, allowing appropriate strategies of screening and prevention. The identification of key molecular actors in the mammary oncogenesis may help to better assess the prognosis of the disease, while providing new therapeutic targets. Large-scale molecular technologies, which allow simultaneous assessment of a high number of molecular parameters in a single assay, should provide new tools to tackle complexity and heterogeneity of breast cancer. Hence, by examining transcriptional profiles of breast cancer using DNA microarrays, it was possible to reveal new prognostic tumor subgroups, previously indistinguishable. Further improvements are awaited with the recent development of high throughput and large-scale technologies investigating the tumor proteome.

PROSPECTS AND PROJECTS

Precise knowledge of molecular alterations involved in each individual breast cancer will allow more effective and less toxic, tailored therapies.

Benign mechanical transport of breast epithelial cells to sentinel lymph nodes

The evaluation of sentinel lymph nodes (SLNs) for the presence of malignant epithelial cells is essential to the staging of breast cancer patients. Recently, increased attention has focused on the possibility that epithelial cells may reach SLNs by benign mechanical means, rather than by metastasis. The purpose of this study was to test the hypothesis that pre-SLN biopsy breast massage, which we currently use to facilitate the localization of SLNs, might represent a mode of benign mechanical transport. We studied 56 patients with invasive and/or in situ ductal carcinoma and axillary SLNs with only epithelial cells and/or cell clusters (< or =0.2 mm in diameter and not associated with features of established metastases) detected predominantly in subcapsular sinuses of SLNs on hematoxylin and eosin- and/or anti-cytokeratin-stained sections. No patient had an SLN involved by either micro- or macro-metastatic carcinoma. Epithelial cells and cell clusters, < or =0.2 mm in size and without features of established metastases, occurred more frequently in the SLNs of patients who underwent pre-SLN biopsy breast massage (P < 0.001, chi2 test). The latter finding supports the hypothesis that pre-SLN biopsy breast massage is a mode of benign mechanical transport of epithelial cells to SLNs.

Modes of benign mechanical transport of breast epithelial cells to axillary lymph nodes

The status of axillary lymph nodes is a key prognostic indicator available for the management of patients with breast cancer. Sentinel lymph node (SLN) evaluation as a predictor of lymph node status has led to increased use of ancillary methods, principally immunohistochemistry, to increase the sensitivity of the SLN biopsy. So-called "occult" micrometastases detected by such methods have led to speculation that some may have reached the SLNs by benign mechanical transport (BMT) rather than a metastatic process. We review evidence suggesting two potential modes of BMT: lymphatic transport of epithelial cells displaced by biopsy of the primary breast tumor and by breast massage-assisted SLN localization. The biopsy techniques under most scrutiny include fine needle aspiration and large-gauge core biopsy. The evidence implicating breast massage prior to SLN biopsy as a mode of BMT has been supported by statistical analysis; however, no method of distinguishing massage-associated cells in SLNs from true occult micrometastases is available. The significance of small epithelial clusters in SLNs is currently unknown. Thus, deviation from current biopsy and SLN-localizing practices is unwarranted.

Missed micrometastatic disease in breast cancer

In the era of sentinel lymph node (SLN) biopsy for breast cancer, ultrastaging by enhanced pathologic techniques (serial sections and/or immunohistochemical [IHC] staining) has become logistically feasible for the first time. Retrospective studies suggest that SLN (and bone marrow) micrometastases detected by these methods are prognostically significant, but controversy still surrounds the significance of micrometastases detected only by IHC, and especially of isolated tumor cells. This heterogeneity among micrometastases may confound the interpretation of current prospective clinical trials that aim to determine their significance. A major challenge for future investigations will be to determine if SLN and bone marrow micrometastases represent similar or distinct biologic phenomena, and whether this distinction will have any implications for treatment.

Predictive Factors for the Status of Non-sentinel Nodes in Breast Cancer Patients with Tumor Positive Sentinel Nodes

In patients with tumor positive sentinel nodes, axillary lymph node dissection is routinely performed while a majority of these patients have no tumor involvement in the non-sentinel nodes. The authors tried to identify a subgroup of patients with a tumor positive sentinel node without non-sentinel node tumor involvement. In 135 consecutive patients with tumor positive sentinel nodes and axillary lymph node dissection performed, the incidence of non-sentinel node involvement according to tumor and sentinel node related factors was examined. The size of the sentinel node metastasis, size of primary tumor and number of tumor positive sentinel nodes were the three factors significantly predicting the status of the non-sentinel nodes. The size of the sentinel node metastasis was the strongest predictive factor (P < 0.0001). In a subgroup of 41 patients with a stage T1 tumor and micrometastatic involvement in the sentinel node only 2 patients (5%) had non-sentinel node involvement. In patients with small primary tumors and micrometastatic involvement of the sentinel nodes, the chance of non-sentinel node involvement is small but cannot be discarded. Because the clinical relevance of micrometastases in lymph nodes is still unclear it is not advisable to omit axillary lymph node dissection even in these patients.

Prognostic factors in breast cancer: current and new predictors of metastasis

Decisions regarding the use of adjuvant therapy for breast cancer are strongly influenced by the risk of disease recurrence and death. These risks are now determined by examining the currently recognized breast cancer prognostic factors, including clinical stage, axillary nodal status, tumor size and grade, hormone receptor status, and presence of lymphovascular involvement. Newer factors are being evaluated in an attempt to more precisely define disease-related prognosis. This paper provides an overview of issues that need to be considered when analyzing studies of prognostic factors as well as a review of the currently recognized and the newer candidate prognostic factors.

Evaluation of axillary sentinel lymph node biopsy by immunohistochemistry and multilevel sectioning in patients with breast carcinoma

BACKGROUND

Axillary lymph node dissection for evaluation of the presence or absence of metastatic disease is the single most important prognostic factor for patients with newly diagnosed primary breast cancer. Recently, sentinel lymph node (SLN) biopsy is being investigated as an alternative to the evaluation of the entire axilla. We evaluated whether the application of multilevel sectioning and immunohistochemistry in SLNs will increase the accuracy of detection of metastatic deposits.

METHODS

Between October 1998 and July 1999, 38 patients with breast carcinoma (25 ductal, 5 lobular, 4 tubular, and 4 mixed ductal and lobular) underwent successful SLN biopsy followed by complete axillary node dissection. Sentinel lymph nodes were localized with a combination of isosulfan blue dye and radionuclide colloid injection. Frozen sections and permanent sections of SLNs were examined. All negative SLNs were examined for micrometastases by 3 additional hematoxylin-eosin (H&E)-stained sections and immunohistochemistry with the cytokeratins AE1/AE3.

RESULTS

Sentinel lymph nodes were successfully identified surgically in 38 (93%) of 41 patients. There was a 97% correlation between the results of the frozen sections and the permanent H&E-stained sections. Twelve (32%) of 38 patients showed evidence of metastatic disease in their SLN by routine H&E staining. In 7 (58%) of 12 patients with positive nodes, the sentinel node was the only positive node. The 26 patients with negative SLN examination by H&E were further analyzed for micrometastases; 5 (19%) were found to have metastatic deposits by immunohistochemistry. Of these patients, 2 were also converted to node positive by detection of micrometastatic disease by examination of the additional H&E levels.

CONCLUSIONS

Sentinel lymph nodes can be accurately identified in the axilla of breast cancer patients. Evaluation of SLNs provides reliable information representative of the status of the axilla in these patients. Immunohistochemistry and, to a lesser degree, detailed multilevel sectioning are able to further improve our ability to detect micrometastatic disease in SLNs of breast cancer patients.

Identification of the sentinel node in patients with breast cancer

Sentinel node analysis represents a significant advance in the diagnosis and treatment of invasive breast cancer. The traditional crude method of full axillary dissection for assessing the status of the axillary nodes can now be discarded in favor of the much more elegant and modern approach of minimally invasive sentinel node analysis and its attendant elimination of the morbidity of traditional axillary node dissection. The many impediments to and pitfalls in the technique of sentinel node analysis, however, must be recognized and overcome for the procedure to be reliable and consistently successful. The use of ultrasound and a smaller particle size can help overcome many of these pitfalls. Because ultrasound identification of the axillary sentinel node in patients with invasive breast cancer is possible, it may allow for percutaneous excision of these nodes in the future (Fig. 8). Combining percutaneous excision and ablation of the primary breast carcinoma with percutaneous excision of the sentinel node allows for the nonsurgical treatment of small breast cancers in the future. The modern breast radiologist should be at the forefront of these advances.