Microvessels that predict axillary lymph node metastases in patients with breast cancer

Inhibition of NADPH oxidase 4 attenuates lymphangiogenesis and tumor metastasis in breast cancer

Lymphangiogenesis is thought to contribute to promote tumor cells to enter lymphatic vessels and plant at a secondary site. Endothelial cells are the cornerstone of the generation of new lymphatic vessels. NADPH oxidase 4 (Nox4) is the most abundant one of NADPH oxidases in endothelial cells and the most studied one in relevance with cancer. Our purpose is to analyze the relationship between Nox4 and lymphangiogenesis and find out whether the newborn lymphatic vessels lead to cancer metastasis. We first explored the expression of Nox4 in lymphatic endothelial cells of primary invasive breast tumors and human normal mammary glands using GEO databases and found that Nox4 was upregulated in primary invasive breast tumors samples. In addition, its high expression correlated with lymph node metastasis in breast cancer patients. Nox4 could increase the tube formation and lymphatic vessel sprouting in a three-dimensional setting. In vivo, inhibition of Nox4 in 4T1 tumor-bearing mice could significantly decrease the tumor lymphangiogenesis and metastasis. Nox4 may increase tumor lymphangiogenesis via ROS/ERK/CCL21 pathway and attract CCR7-positive breast cancer cells to entry lymphatic vessels and distant organs. In conclusion, our results show that Nox4 is a factor that promotes lymphangiogenesis and is a potential target of antitumor metastasis.

Clinicopathological Evaluation of the Potential Anatomic Pathways of Systemic Metastasis from Primary Breast Cancer Suggests an Orderly Spread Through the Regional Lymph Nodes

Background

Two conflicting hypotheses as to how breast cancer (BC) accesses the systemic circulation dominated the 20th century and affected surgical treatment. We hypothesized that tumor lymphovascular invasion (LVI) at the primary tumor site favors lymphatic and not blood vessel, capillaries, and systemic metastases (Smets) are dependent upon regional lymph node (RLN) mets.

Methods

Data from BC patients undergoing RLN biopsy was professionally abstracted and maintained in a prospective, precisely managed, single-institution database. Associations of RLN, LVI, and Smets were estimated by univariate and multivariate backward logistic regression models and patient-affiliated demographic, clinicopathologic, treatment type, and molecular marker data.

Results

Of 3329 patients, followed 1–22 years (mean 7.8), 463 of 3329 (13.9%) showed LVI, 742 of 3329 (22.3%) had RLN mets, and 262 of 3329 (7.9%) had Smets. Smets occurred in 52 of 252 (21% with LVI+/RLN+); 116 of 2301 (5% with LVI−/RLN−); 65 of 465 (14% with LVI−/RLN+); and 17 of 207 (8% with LVI+/RLN−), p = 0.021 for association between LVI and Smets for RLN+ patients but not for RLN− patients (p = 0.051). Positive RLN, larger tumor size, and higher grade (all p < 0.001) were predictive of Smets by the multivariable model, whereas positive LVI was not.

Conclusions

LVI predicts RLN mets in BC. RLN is critical to Smets from BC, whereas LVI on its own is not. Smets occur significantly more commonly when both LVI and RLN mets occur together. LVI is, thus, likely to be primarily lymphatic invasion, and rarely, blood vessel invasion, supporting the Halsted paradigm. LVI and RLN together predict clinical outcome better than either alone.

Graphic Abstract

Prognostic Value of Lymphangiogenesis Determinants in Luminal and Non-luminal Breast Carcinomas

Background:

Breast carcinomas (BCs) are sub-classified according to the molecular characteristics into luminal and non-luminal subtypes that clinically show different biological behavior, treatment and prognosis. BCs spread primarily through lymphatic vessels using cascade processes of lymphagiogenesis in which VEGF-C plays an important role during lymph node metastasis. Prognostic value of VEGF-C in luminal and non-luminal BC is still unclear and has not been studied thoroughly to clarify and define prognosis and therapeutic monitoring.

Aim:

To define the prognostic value of lymphangiogenesis on survival rates of luminal and non-luminal subtypes BC.

Materials and Methods:

This study applied prospective cohort design, using 130 patients of invasive duct carcinoma of the breast, stage I-IIIA, from Sardjito General Hospital, Indonesia and subsequent longitudinal follow-up. Immunohistochemical staining was carried out using anti-ER, -PR, -Her-2, VEGF-C, VEGFR-3 and D2-40 antibodies. The related clinicopathologic characteristics of BC patients and lymphangiogenesis determinants, including VEGF-C expression, were statistically analyzed.

Results:

In non-luminal BC subtypes, VEGF-C expression (HR=0.04; 95% CI=0.01-0.41), lymph node metastasis (HR=0.14; 95% CI=0.04-0.55) and stage (HR=0.30; 95% CI= 0.02-0.76) were determined as independent prognostic factors on survival rates. However, the lymphangiogenesis determinants were not associated with the survival rates of luminal BC subtypes.

Conclusion:

This study suggested that lymphangiogenesis affects survival rates of non-Luminal subtype rather than the luminal subtypes of BC.

The relationship of lymphatic vessel density, lymphovascular invasion, and lymph node metastasis in breast cancer: a systematic review and meta-analysis

Lymph node status is one of the key parameters used for determining the stage of breast cancer progression. The relationship of lymphatic vessel density (LVD), lymphovascular invasion (LVI), and lymph node metastasis (LNM) has not been clearly demonstrated yet. Databases of PubMed, Embase, and Web of Science were searched from inception up to 25 May 2016. Spearman correlation coefficient (r) and 95% confidence interval (CI) were used to determine the relationship within each group. Based on pre-established inclusion criteria, 28 studies involving 2920 breast cancer patients were included in this study. The r values of LVD-LVI, LVD-LNM, and LVI-LNM were 0.45 (95% CI: 0.31 to 0.57), 0.32 (95% CI: 0.23 to 0.40), and 0.24 (95% CI: 0.19 to 0.28), respectively. Compared with intratumoral LVD, peritumoral LVD showed more robust correlation with LVI (r = 0.53, 95% CI: 0.27 to 0.72) and LNM (r = 0.33, 95% CI: 0.18 to 0.46). The patients in LNM positive group presented with higher LVI detection rate of 45.85%, while in LNM negative group with detection rate of 23.85%. The results describe a triangle relationship between LVD, LVI, and LNM in breast cancer. Both LVD and LVI are indicated to be valuable predictors of LNM occurrence. Compared with intratumoral lymphatic vessels, peritumoral lymphatics might be the main disseminate route for breast tumor cells.

Effect of lymphangiogenesis and lymphovascular invasion on the survival pattern of breast cancer patients

BACKGROUND

Invasion of breast cancer cells into blood and lymphatic vessels is one of the most important steps for metastasis. In this study the prognostic relevance of lymphangiogenesis and lymphovascular invasion (LVI) in breast cancer patients was evaluated in terms of survival.

MATERIALS AND METHODS

This retrospective study concerned 518 breast cancer patients who were treated at Department of Surgical Oncology, Saroj Gupta Cancer Centre and Research Institute, Kolkata-700063, West Bengal, India, a reputed cancer centre and research institute of eastern India between January 2006 and December 2007.

RESULTS

The median overall survival and disease free survival of the patients were 60 months and 54 months respectively. As per Log-rank test, poor overall as well as disease free survival pattern was observed for LVI positive patients as compared with LVI negative patients (p<0.01). Also poor overall as well as disease free survival pattern was observed for perineural invasion (PNI) positive patients as compared to PNI negative patients (p<0.01).

CONCLUSIONS

From this study it is evident that LVI and PNI are strongly associated with outcome in terms of disease free as well as overall survival in breast cancer patients. Thus LVI and PNI constitute potential targets for treatment of breast cancer patients. We advocate incorporating their status into breast cancer staging systems.

Clinicopathological significance of lymphangiogenesis detected by immunohistochemistry using D2-40 monoclonal antibody in breast cancer

To elucidate the association between the lymphangiogenesis and clinicopathological factors including the survival in breast cancer, 91 Japanese patients with breast cancer were investigated.　The lymphangiogenesis was evaluated by the count of lymph vessel density (LVD) with immunohistochemical method using D2-40 monoclonal antibody, a specific marker for lymphatic endothelial cells.D2-40-positive lymph vessels were detected in 87 of 91 cases, and were mainly distributed in the peritumoral lesions or around the tumor edge.　There was a significant difference in disease-free survival (DFS) and overall survival (OS) between patients with high LVD and with low LVD (p=0.02, 0.01, respectively, log-rank test).　In addition, LVD significantly correlated with the following clinicopathological factors: menopausal status (p<0.01), tumor size (p<0.01), lymph-node status (p=0.01) lymphatic vessel invasion (LVI) (p<0.01), blood vessel invasion (BVI) (p=0.03) and estrogen receptor status (ER) (p=0.02).Those data suggest that D2-40 monoclonal antibody is a useful marker for evaluating the LVD and its evaluation is helpful to predict the survival in breast cancer.

[The role of nipple-sparing mastectomy in breast cancer: a comprehensive review of the literature]

BACKGROUND

The role of nipple-sparing mastectomy (NSM) for breast cancer is controversial as there is concern regarding its oncological safety and complication rate. We carried out a review of the literature to quantify the incidence of occult nipple malignancy in breast cancer, identify the factors influencing occult nipple malignancy, quantify locoregional recurrence rates and quantify NSM complication rates.

METHODS

A search of the literature was performed using PubMed. Keywords used were "mastectomy", "nipple involvement", "nipple-sparing mastectomy", "skin-sparing mastectomy" "occult nipple malignancy" "occult nipple disease" "breast cancer recurrence". Articles were analyzed regarding incidence of occult nipple malignancy, potential factors influencing the incidence of occult malignancy and recurrence/complications following NSM. The incidence of occult nipple disease was compared between groups using Chi(2) or Fisher's exact tests for categorical variables and Student's t-tests for continuous variables. P values were considered significant<0.05. We identified nearly 30 studies compiling nearly 10 000 cases examining the rate of occult nipple malignancy and 23 studies compiling 2300 cases providing information on the rate of local recurrence after NSM.

RESULTS

The overall rate of occult nipple malignancy was 11.5 %. Primary tumour characteristics influencing occult nipple malignancy were tumour-nipple distance<2cm, grade, lymph node metastasis, lymphovascular invasion, HER2 positive, ER/PR negative, tumour size>5cm, retro-areolar/central location and multicentric tumours. The overall nipple recurrence rate following NSM was 0.9 %, skin flap recurrence rate was 4.2 %. Full and partial thickness nipple necrosis rates were 2.9 % and 6.3 % respectively.

CONCLUSION

NSM for primary breast cancer is appropriate in carefully selected patients. All patients should have retro-areolar sampling. There is strong evidence to suggest that suitable cases are well circumscribed single or multifocal lesions that have a TND>2cm. Tumours should be graded 1-2 and not have LVI, axillary node metastasis or HER2 positivity.

Differences in sonographic features of papillary thyroid carcinoma between neck lymph node metastatic and nonmetastatic groups

OBJECTIVES

The purpose of this study was to assess the differences in sonographic features of papillary thyroid carcinoma between neck lymph node metastatic and non-metastatic groups.

METHODS

A total of 155 patients with 155 papillary thyroid carcinoma nodules were included and divided into two groups: with neck lymph node metastases (52 cases) and without neck lymph node metastases (103 cases). The size, shape, border, margin, halo, internal architecture, echogenicity, echo homogeneity, calcifications, and contact extent between the nodule border and thyroid capsule were evaluated by gray scale sonography, and color Doppler sonography was applied to assess the vascularization distribution and vascularization degree in the nodules. The peak systolic velocity, pulsatility index, resistive index, peak systolic velocity difference, pulsatility index difference, and resistive index difference were measured by pulsed Doppler sonography in 80 lesions. The differences in the sonographic features of papillary thyroid carcinoma between the metastatic and nonmetastatic groups were investigated.

RESULTS

The differences in the size, percentage of the nodule border that contacted the thyroid capsule, calcifications, vascularization degree, and resistive index difference of the lesions were statistically significant between the metastatic and nonmetastatic groups (P < .05).

CONCLUSIONS

Our findings suggest that a larger size, a greater contact percentage, combined microcalcifications and macrocalcifications, a higher blood supply, and a higher resistive index difference were significantly more common in the metastatic group compared to the nonmetastatic group.

The extent of retraction clefts correlates with lymphatic vessel density and VEGF-C expression and predicts nodal metastasis and poor prognosis in early-stage breast carcinoma

Although the earliest feature of disseminated disease in breast cancer is regional lymph node involvement, little is known about the mechanisms whereby cancer cells interact with lymphatic endothelial cells and enter the lymphatic system. We have previously reported that the extensive presence of retraction clefts in breast carcinomas highly significantly correlates with lymphatic tumor spread and predicts poor outcome, suggesting that retraction clefts are not just fixation artifacts, but real potential spaces that are exaggerated by tissue processing and may reflect an early stage of lymphatic invasion. In this study, we examined the correlation between the extent of retraction clefts and lymphangiogenesis, as assessed by lymphatic vessel density and vascular endothelial growth factor-C (VEGF-C) expression in a series of 256 early-stage breast carcinomas. The presence and extent of retraction clefts around tumor cell nests was determined by review of all hematoxylin- and eosin-stained tumor sections. Lymphatic vessels were detected by podoplanin immunohistochemistry and lymphatic vessel density was measured using the hot-spot method. The expression of VEGF-C in the tumor cells was determined by immunohistochemistry and analyzed semiquantitatively on a four-tiered scale. High levels of retraction clefts, peritumor lymphatic vessel density and VEGF-C expression at the invasive edge in breast carcinomas significantly correlated with tumor size, histological grade, lymphatic invasion and nodal metastasis. Breast carcinomas showing extensive retraction clefts (>20% of tumor volume) were found to have significantly higher lymphatic vessel density and VEGF-C expression levels compared to tumors without this feature. High retraction clefts, peritumor lymphatic vessel density and VEGF-C expression predicted poor outcome in breast carcinomas. Our results support the hypothesis that retraction clefts are real potential spaces that may represent 'pre-lymphatic spaces' facilitating initial lymphatic invasion and that growth factors secreted by the tumor cells may stimulate tumor-associated lymphangiogenesis by promoting the endothelialization of these 'pre-lymphatic channels'.

The role of lymph node metastasis in the systemic dissemination of breast cancer

BACKGROUND.: Lymphatic invasion is necessary for regional lymph node (RLN) metastasis in breast cancer (BC), while systemic metastasis requires blood vessel (BV) invasion. The site of BV invasion could be at the primary BC site or through lymphovascular anastomoses. The vague pathologic term "lymphovascular invasion" (LVI) encourages the belief that peri/intratumoral BV invasion may be common. We investigated the relative contribution of RLN metastasis to systemic metastasis by studying the relationship among LVI and RLN and/or systemic metastasis in a population-based cohort of breast cancer patients. METHODS.: Fisher's exact test was done to assess global associations among LVI and RLN and/or systemic metastasis in a prospective database of breast cancer patients undergoing RLN biopsy. Logistic regression was used to determine multivariable contributions of LVI to metastasis when controlling for available demographic, radiologic, and pathologic variables. RESULTS.: Of 1668 patients evaluated 25.4% were RLN positive and 10.4% had LVI. RLN metastasis was predicted by tumor size (P < .0001), HER-2/neu overexpression (P = .0022) and the interaction between LVI positive and HER-2/neu positive tumors (< .0001). Patients with LVI/HER-2-neu positive were 3 times as likely to have positive RLNs compared with patients LVI/HER-2-neu negative. Systemic metastasis was significantly (P = .0013) associated with LVI/ RLN positive, but not with LVI positive/RLN negative patients (P = .137). CONCLUSIONS.: LVI predicted RLN metastasis. LVI also significantly predicted systemic metastasis, but only when the RLN was also positive. Since RLN requires lymphatic invasion, these data support the hypothesis that primary breast cancers often invade lymphatics to gain access to the systemic circulation.

Vascular endothelial growth factor receptors VEGFR-2 and VEGFR-3 are localized primarily to the vasculature in human primary solid cancers

PURPOSE

Vascular endothelial growth factor (VEGF) signaling is key to tumor angiogenesis and is an important target in the development of anticancer drugs. However, VEGF receptor (VEGFR) expression in human cancers, particularly the relative expression of VEGFR-2 and VEGFR-3 in tumor vasculature versus tumor cells, is poorly defined.

EXPERIMENTAL DESIGN

VEGFR-2- and VEGFR-3-specific antibodies were identified and used in the immunohistochemical analysis of human primary cancers and normal tissue. The relative vascular localization of both receptors in colorectal and breast cancers was determined by coimmunofluorescence with vascular markers.

RESULTS

VEGFR-2 and VEGFR-3 were expressed on vascular endothelium but not on malignant cells in 13 common human solid tumor types (n > 400, bladder, breast, colorectal, head and neck, liver, lung, skin, ovarian, pancreatic, prostate, renal, stomach, and thyroid). The signal intensity of both receptors was significantly greater in vessels associated with malignant colorectal, lung, and breast than adjacent nontumor tissue. In colorectal cancers, VEGFR-2 was expressed on both intratumoral blood and lymphatic vessels, whereas VEGFR-3 was found predominantly on lymphatic vessels. In breast cancers, both receptors were localized to and upregulated on blood vessels.

CONCLUSIONS

VEGFR-2 and VEGFR-3 are primarily localized to, and significantly upregulated on, tumor vasculature (blood and/or lymphatic) supporting the majority of solid cancers. The primary clinical mechanism of action of VEGF signaling inhibitors is likely to be through the targeting of tumor vessels rather than tumor cells. The upregulation of VEGFR-3 on tumor blood vessels indicates a potential additional antiangiogenic effect for dual VEGFR-2/VEGFR-3-targeted therapy.

The role of lymph node metastasis in the systemic dissemination of breast cancer

BACKGROUND

Lymphatic invasion is necessary for regional lymph node (RLN) metastasis in breast cancer (BC), while systemic metastasis requires blood vessel (BV) invasion. The site of BV invasion could be at the primary BC site or through lymphovascular anastomoses. The vague pathologic term "lymphovascular invasion" (LVI) encourages the belief that peri/intratumoral BV invasion may be common. We investigated the relative contribution of RLN metastasis to systemic metastasis by studying the relationship among LVI and RLN and/or systemic metastasis in a population-based cohort of breast cancer patients.

METHODS

Fisher's exact test was done to assess global associations among LVI and RLN and/or systemic metastasis in a prospective database of breast cancer patients undergoing RLN biopsy. Logistic regression was used to determine multivariable contributions of LVI to metastasis when controlling for available demographic, radiologic, and pathologic variables.

RESULTS

Of 1668 patients evaluated 25.4% were RLN positive and 10.4% had LVI. RLN metastasis was predicted by tumor size (P < .0001), HER-2/neu overexpression (P = .0022) and the interaction between LVI positive and HER-2/neu positive tumors (< .0001). Patients with LVI/HER-2-neu positive were 3 times as likely to have positive RLNs compared with patients LVI/HER-2-neu negative. Systemic metastasis was significantly (P = .0013) associated with LVI/RLN positive, but not with LVI positive/RLN negative patients (P = .137).

CONCLUSIONS

LVI predicted RLN metastasis. LVI also significantly predicted systemic metastasis, but only when the RLN was also positive. Since RLN requires lymphatic invasion, these data support the hypothesis that primary breast cancers often invade lymphatics to gain access to the systemic circulation.

[Molecular aspects of lymph node metastasis]

The risk of local and systemic lymphatic metastasis of a tumor increases with the size of the malignant neoplasia. Lymph vessels are generated in the tumor and seem to follow anatomically defined pathways. However, the precise molecular and biological mechanisms seem to be complex and require definition. At present, molecules belonging to the vascular endothelial growth factors family and podoplanin have been identified as key for the proliferation of the tumor's lacteals. Molecular mechanisms of the tumor origin and the hematogenic and lymphatic dissemination are increasingly better defined by the use of new diagnostic and therapeutic approaches for tumor patients. Simultaneously, we might be able to influence processes such as cell growth, apoptosis, angiogenesis, and lymphogenic dissemination by novel drugs and thereby develop novel approaches for tumor treatment. Chemokine receptors seem to control essential steps of lymphogenic dissemination such as migration, invasion, and proliferation of tumor cells.

A novel gene expression profile in lymphatics associated with tumor growth and nodal metastasis

Invasion of lymphatic vessels is a key step in the metastasis of primary tumors to draining lymph nodes. Although the process is enhanced by tumor lymphangiogenesis, it is unclear whether this is a consequence of increased lymphatic vessel number, altered lymphatic vessel properties, or both. Here we have addressed the question by comparing the RNA profiles of primary lymphatic endothelial cells (LEC) isolated from the vasculature of normal tissue and from highly metastatic T-241/vascular endothelial growth factor (VEGF)-C fibrosarcomas implanted in C57BL/6 mice. Our findings reveal significant differences in expression of some 792 genes (i.e., >or=2-fold up- or down-regulated, P <or= 0.05) that code for a variety of proteins including components of endothelial junctions, subendothelial matrix, and vessel growth/patterning. The tumor LEC profile, validated by immunohistochemical staining, is distinct from that of normal, inflammatory cytokine, or mitogen-activated LEC, characterized by elevated expression of such functionally significant molecules as the tight junction regulatory protein endothelial specific adhesion molecule (ESAM), the transforming growth factor-beta coreceptor Endoglin (CD105), the angiogenesis-associated leptin receptor, and the immunoinhibitory receptor CD200, and reduced expression of subendothelial matrix proteins including collagens, fibrillin, and biglycan. Moreover, we show similar induction of ESAM, Endoglin, and leptin receptor within tumor lymphatics in a series of human head and neck and colorectal carcinomas, and uncover a dramatic correlation between ESAM expression and nodal metastasis that identifies this marker as a possible prognostic indicator. These findings reveal a remarkable degree of phenotypic plasticity in cancer lymphatics and provide new insight into the processes of lymphatic invasion and lymph node metastasis.

Molecular mechanisms of metastasis

A major topic covered at the First International Symposium on Cancer Metastasis and the Lymphovascular System was the molecular mechanisms of metastasis. This has become of major interest in recent years as we have discovered new metastasis-related genes and gained understanding of the molecular events of lymphatic metastasis. The symposium covered new aspects and important questions related to the events of metastasis in both humans and animals. The basic and clinical related research covered in this topic represented many disciplines. The presentations showed novel findings and at the same time, raised many new unanswered questions, indicating the limited knowledge we still have regarding the molecular events of metastasis. The hope is that further unraveling of the direct and indirect molecular events of lymphatic metastasis will lead to new approaches in developing effective therapeutics.

A quantitative analysis of lymphatic vessels in human breast cancer, based on LYVE-1 immunoreactivity

This study was undertaken to determine the highly sensitive method for detecting tumour lymphatic vessels in all the fields of each slide (LV), lymphatic microvessel density (LMVD) and lymphatic vessel invasion (LVI) and to compare them with other prognostic parameters using immunohistochemical staining with polyclonal (PCAB) and monoclonal antibodies (MCAB) to the lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), and the pan-endothelial marker factorVIII in a series of 67 human breast cancers. In all LYVE-1-stained sections, LV (some of which contained red blood cells) were frequently found localised in extralobular stroma, dermis, connective tissue stroma and adjacent to artery and vein, but were rare within the intralobular stroma or the tumour body (3/67 cases) or areas of widespread invasion. In contrast small blood vessels were observed in intra- and extralobular stroma in the factor VIII-stained sections. Quantitation of vessel numbers revealed that LYVE-1/PCAB detected a significantly larger number of LV than either H&E or LYVE-1/MCAB (P<0.0001). LYVE-1/PCAB detected LVI in 25/67 cases (37.3%) and their presence was significantly associated with both lymph node metastasis (χ²=4.698, P=0.0248) and unfavourable overall survival (OS) (P=0.0453), while not relapse- free survival (RFS) (P=0.2948). LMVD had no influence for RFS and OS (P=0.4879, P=0.1463, respectively). Our study demonstrates that immunohistochemistry with LYVE-1/PCAB is a highly sensitive method for detecting tumour LV/LVI in breast cancer and LVI is a useful prognostic indicator for lymphatic tumour dissemination.

Lymphangiogenesis in human gynaecological cancers

The metastatic spread of tumor cells is responsible for the majority of cancer deaths, and with few exceptions, all cancers can metastasize. Clinical findings have for a long time suggested that by providing a pathway for tumor cell dissemination, tumor-associated lymphatics act as key components of metastatic spread. This is believed to occur principally via pre-existing and possibly also newly formed lymphatics (lymphangiogenesis). Increased expression of vascular endothelial growth factor-C (VEGF-C) and VEGF-D in primary tumors correlates with increased dissemination of tumor cells to regional lymph nodes (LNs) in a variety of human carcinomas. Here we will review the mechanisms of lymphangiogenesis, particularly in the context of metastatic tumor spread, and will critically examine the role of VEGF-C and VEGF-D in this process in gynaecological cancers. Potential anti-lymphangiogenic strategies are also discussed.

Molekularbiologische Erklärungsansätze einer Lymphknotenmetastasierung

The spread of tumor cells of solid tumors to the regional lymph nodes is an important step in the progression of the disease and also an important prognostic factor. While the significance of the prognostic value of the lymphatic progression had been detected long ago, only increased knowledge of the molecular anatomy and mechanisms involved in the lymphatic spread of tumor cells provided a beginning insight into the understanding of lymphatic metastasis. One group of important molecular factors consists of proteins produced by the tumor cells inducing a proliferation of lymphatic vessels into the primary tumor. The vascular endothelial growth factors have been identified as key factors in this process. In addition there are hints for the fact that chemokines, which are cytokine-like proteins taking part in the regulation of processes of inflammation, and their chemokine receptors control cellular key steps of lymphatic metastasis of tumor cells such as migration, proliferation, and invasion. In conclusion new data point to the possible inhibition of lymphatic spread by selective blockade of growth factor receptors or chemokine receptors. The growing insight into cellular understanding of the mechanisms involved in the metastasis of tumor cells into the lymphatics and lymph nodes will hopefully facilitate the development of new diagnostic and therapeutic tools in the treatment of cancer patients.

VEGFR-3 expression in breast cancer tissue is not restricted to lymphatic vessels

We examined the immunohistochemical reactivity for vascular endothelial growth factor receptor 3 (VEGFR-3), a protein playing an important role in lymphangiogenesis, in breast cancer. A retrospective series of 77 invasive ductal breast carcinomas was investigated. The relationship between VEGFR-3 expression and clinicopathologic parameters was examined for statistical significance using Pearson's chi-square (chi2) test and Fisher's exact test (when n<5). Threshold for significance was p<0.05. Patient age ranged from 31 to 77 years (mean: 55 years). The VEGFR-3 immunoreactivity was as follows: 5 cases were negative (6.5%), 35 + (45.4%), 27+ + (35.1%), and 10+ + + (13.0%). Reactions were positive for both lymphatic and blood vessels in several cases. VEGFR-3-positive reactions were more frequent in the tumor periphery than within the tumor. Immunoreactivity was also observed in myoepithelial cells surrounding both normal ducts and ducts with ductal carcinoma in situ. Statistical analysis of VEGFR-3 reactions was not significantly related to node status, microvessel density, and tumor grade. Ploidy showed a tendency towards significance (p=0.063); however, owing to the limited number of cases, statistical significance was not reached. VEGFR-3 lacks lymphatic vessel specificity and is also expressed in blood vessels, myoepithelial cells, and neoplastic cells.

Prognostic value of lymphangiogenesis and lymphovascular invasion in invasive breast cancer

OBJECTIVE

The aim of this study was to investigate the prognostic relevance of lymphangiogenesis and lymphovascular invasion in a large cohort of breast cancer patients.

INTRODUCTION

Invasion of tumor cells into blood and lymphatic vessels is one of the critical steps for metastasis. The presence or absence of lymph node metastasis is one of the main decision criteria for further therapy. One shortcoming of previous morphologic studies was the lack of specific markers that could exact discriminate between blood and lymphatic vessels. The aim of this study was to evaluate the prognostic relevance of lymphangiogenesis and lymphovascular invasion in breast cancer patients.

METHODS

We investigated 374 tissue specimens of patients suffering from invasive breast cancer by immunostaining for the lymphatic endothelial specific marker podoplanin. Lymphangiogenesis, quantified by evaluating the lymphatic microvessels density (LMVD), and lymphovascular invasion (LVI) were correlated with various clinical parameters and prognostic relevance.

RESULTS

LMVD correlated significantly with LVI (P = 0.001). LVI was associated significantly with a higher risk for developing lymph-node metastasis (P = 0.004). Calculating the prognostic relevance, LVI presented as an independent prognostic parameter for disease free as well as overall survival (P = 0.001, and P = 0.001, respectively).

CONCLUSION

Our data provide evidence that the biologic system of lymphangiogenesis constitutes a potential new target for development of anti-breast cancer therapeutic concepts. Our results further suggest that young, premenopausal patients with low differentiated breast tumors and high LMVD and LVI would, in particular, benefit from lymphangiogenesis-associated therapeutic strategies.

Insights into the mechanisms of lymph node metastasis

The mechanisms by which malignant tumors leave the primary tumor site, invade lymphatics, and metastasize to regional lymph nodes (RLNs) are complex and interrelated. Although the phenomenon of lymph node metastasis has been recognized for over 200 years, the exact mechanisms have only recently been the subject of intense interest and sophisticated experimentation. Sentinel lymph node biopsy has rapidly entered the clinical mainstream for melanoma and breast carcinoma, and this technique has provided confirmation of the orderly anatomic progression of tumor cells from primary site to the RLNs through lymphatic capillaries and trunks. Exciting studies involving the pathophysiology of interstitial fluid pressure in tumors and the peritumoral extracellular matrix have focused on lymphatic flow and tumor microenvironment and microcirculation. Molecular techniques have led to the definition of unique markers found on lymphatic endothelial cells. These markers have enabled scientists to identify peritumoral and intratumoral lymphatics and to visualize the ingrowth of tumor cells into the lumena of lymphatic capillaries. Tumor-secreted cytokines, such as vascular endothelial growth factors (VEGF)-C and -D, bind to VEGF receptors on lymphatic endothelial cells and induce proliferation and growth of new lymphatic capillaries; this process is similar to the well-known mechanism of angiogenesis, which results from the proliferation of new blood vessel capillaries. Lymphangiogenesis is associated with an increased incidence of RLN metastasis, and it is possible that this step is essential to the metastatic process. Directional movement toward lymphatics and lymph nodes appears to follow a chemokine gradient, and it is likely that some tumor cells that express certain types of chemokine receptors are more likely to metastasize to the RLNs. In contrast, tumor cells that do not express specific receptors that are responsive to lymphatic chemokines may not metastasize. New knowledge regarding the molecules involved in these processes should enable improvements in prognostic and possibly therapeutic approaches to the management of malignant tumors.

Absence of lymphangiogenesis and intratumoural lymph vessels in human metastatic breast cancer

Early metastasis to lymph nodes is a frequent complication in human breast cancer. However, the extent to which this depends on lymphangiogenesis or on invasion of existing lymph vessels remains controversial. Although proliferating intratumoural lymphatics that promote nodal metastasis have been demonstrated in experimental breast tumours overexpressing VEGF-C, it has yet to be determined whether the same phenomena occur in spontaneous human breast cancers. To address this important issue, the present study investigated the lymphatics in primary human breast carcinoma (75 cases of invasive ductal and lobular breast cancer) by quantitative immunohistochemical staining for the lymphatic endothelial hyaluronan receptor LYVE-1, the blood vascular marker CD34, and the nuclear proliferation marker pKi67. None of the breast carcinomas was found to contain dividing lymph vessels, even in areas of active haemangiogenesis. Furthermore, the majority of non-dividing lymph vessels were confined to the tumour periphery where their incidence was low and unrelated to tumour size, grade or nodal status; rather, their density was inversely correlated with tumour aggressiveness as assessed by macrophage density (p = 0.009), and blood microvessel density (p = 0.05, Spearman Rank), as well as with distance from the tumour edge. Finally, a proportion of the peritumoural lymphatics contained tumour emboli associated with hyaluronan, indicating a possible role for LYVE-1/hyaluronan interactions in lymphatic invasion or metastasis. These results suggest that naturally occurring breast carcinomas invade and destroy lymph vessels rather than promoting their proliferation; that breast tumour lymphangiogenesis may not always occur at physiological VEGF-C levels; and that nodal metastasis can proceed via pre-existing lymphatics.

Lymphangiogenesis in tumors: what do we know?

Lymphangiogenesis, the growth of new lymphatic vessels, has long been regarded as a putative efficient pathway to neoplastic metastization. However, until recently consistent data regarding reliable lymphatic endothelial cell markers were lacking. Moreover, the presence of new formed lymphatic vessels was considered a largely disputable concept. Now, this scenario has changed significantly, owing to consistent reports describing novel lymphatic endothelial cell (LEC) markers, the demonstration of new formed lymphatic vessels within the bulk of the tumor in animal models and human neoplasms, and the characterization of the VEGF-C/VEGFR-3 pathway. We herein review the major breakthroughs in the field of lymphangiogenesis, with special emphasis on novel and reliable LEC markers, such as prox-1, LYVE-1, and podoplanin, as well as on the pathological assessment of lymphangiogenesis as a putative prognostic factor for human neoplasms.

Angiogenesis in patients with craniopharyngiomas: correlation with treatment and outcome

BACKGROUND

Craniopharyngiomas are histologically benign epithelial neoplasms of the sellar region that often exhibit aggressive and invasive growth. The authors hypothesized that tumor proliferation, spread, and recurrence are angiogenesis dependent and investigated the significance of vascularization relative to biologic behavior. To the authors' knowledge, angiogenesis for patients with craniopharyngiomas has not been examined to date.

METHODS

The authors measured microvessel densities in resected, histologically proven craniopharyngiomas using immunostains for CD-34, a monoclonal antibody that selectively recognizes endothelial cells. Both histologic types of craniopharyngiomas, adamantinomatous and papillary, were included in the study. In addition, the cellular distribution of vascular endothelial growth factor (VEGF), a strong stimulator of new vessel formation, was assessed by both immunohistochemistry and in situ hybridization for VEGF receptor 2 (VEGFR-2) mRNA expression.

RESULTS

Histologically, small numbers of capillaries were identified in temporal stroma but not in their epithelial components. Immunohistochemistry revealed strong, conclusive cytoplasmic immunoreactivity for VEGF in the epithelial cells of both adamantinomatous craniopharyngiomas and papillary craniopharyngiomas. In situ hybridization showed that VEGFR-2 mRNA was expressed widely, not only in neoplastic epithelium but also in capillary endothelium.

CONCLUSIONS

Tumors with greater microvessel density regrow more frequently compared with tumors that have lower microvessel density, suggesting that the extent of angiogenesis is of prognostic value in patients with craniopharyngioma. VEGFR-2 may act as a key modulator of VEGF activity in endothelial cells and nonendothelial cells, indicating that VEGF plays an important role in the behavior of craniopharyngiomas.

Pathways of lymphatic drainage from the breast

BACKGROUND

The current standard for obtaining accurate sentinel lymph node (SLN) mapping is intraparenchymal lymphophilic dye/radiocolloid injection close to the breast tumor. We hypothesized that common lymphatic trunks drain both a large volume of breast parenchyma and skin and that intradermal or intraparenchymal routes flow to the same axillary node.

METHODS

99mTc-labeled filtered sulfur colloid was injected intradermally directly over the breast tumor in 119 patients. Blue dye was injected intraparenchymally in the same quadrant as the primary tumor (concordant quadrant) in 66 and in a discordant quadrant in 53 patients. During axillary exploration, both blue and gamma-emitting (hot) nodes were found. End points were SLNs that were hot and blue, either the same node or different nodes.

RESULTS

In 62 (93.9%) of 66 of concordant quadrant and in 49 (92.5%) of 53 of discordant quadrant patients, the same SLN was both hot and blue (P = .99; Fisher's exact test). In eight cases in which two distinct nodes were blue and not hot and hot but not blue, the lymph nodes were very close to each other.

CONCLUSIONS

The dermal and parenchymal lymphatics of the breast seemed to drain to the same axillary lymph nodes. Lymph from the entire breast seemed to drain through a small number of lymphatic trunks to one or two lymph nodes.