Lymphatic microvessel density as a novel prognostic factor in early-stage invasive cervical cancer

Clinical significance of CD34, podoplanin and Ki-67 expression in patients with locally advanced squamous cell cervical carcinoma

The aim of the study was to assess immunohistochemical CD34, podoplanin and Ki-67 expression in cervical tumour of patients with cervical squamous cell carcinoma (SCC) staged IIB and IIIB, a relationship with selected clinical and histological parameters and its prognostic significance. This prospective study included 52 patients. Microvessel density (MVD) by CD34, lymphatic vessel density (LVD) by podoplanin and the Ki-67 index in specimens from paraffin blocks with cervical SCC tissues were examined. The relationship between these data and selected clinical and histological parameters was analysed. Positive correlation of MVD and the Ki-67 index was observed. No correlation was observed for MVD, LVD and the Ki-67 index in the tumour with staging, grading, length of treatment and squamous cell carcinoma antigen (SCC-Ag) concentration before and after treatment. The expression of MVD, LVD and the Ki-67 index in cervical SCC did not contribute to the risk of relapse and cancer-related death. No relationship was found for MVD, LVD and the Ki-67 index in cervical tumour of patients with locally advanced cervical SCC with staging, grading and serum SCC-Ag level. MVD, LVD and the Ki-67 index in the tumour did not contribute to the risk of relapse or cervical SCC-related death.Impact StatementWhat is already known on this subject? In many patients, invasive cervical squamous cell carcinoma (SCC) is diagnosed in a locally advanced stage, when the prognosis depends on many well-known factors connected with tumour biology, staging and general condition of the patient. Despite numerous studies, the value of immunohistochemical CD34, podoplanin and Ki-67 expression in cervical tumour of these patients is still not well defined.What do the results of this study add? In our prospective study, no relationship for microvessel density (MVD), lymphatic vessel density (LVD) and the Ki-67 index in cervical tumour of patients with locally advanced cervical SCC with staging, grading and serum squamous cell carcinoma antigen (SCC-Ag) level was found. Additionally, MVD, LVD and the Ki-67 index in the tumour did not contribute to the risk of relapse or cervical SCC-related death.What are the implications of these findings for clinical practice and/or further research? Our study underlines the limited value of immunohistochemical CD34, podoplanin and Ki-67 expression in cervical tumour of patients with locally advanced cervical SCC. Further research should be focussed on identifying and validating novel prognostic and predictive factors.

Expression of podoplanin in tumor cells and lymphatic vessels in both tumoral and peritumoral areas and correlation with metastatic potential of oral squamous cell carcinoma

Aim:

This study aims to study the expression of podoplanin in tumor cells as well as the lymphatic vessels (LVs) in both tumoral and peritumoral areas and correlate the importance of the lymphatic microvascular density (LMVD) in oral squamous cell carcinoma (OSCC) and its metastatic potential.

Materials and Methods:

D2–40 expression and LV density (LVD) were assessed using antibody D240, in 45 diagnosed cases of all the three grades of OSCC. D2–40 expression was evaluated in both epithelial cells as well as the LVs.

Results:

D2–40 expression in OSCC showed two different patterns - diffuse and focal. LMVD was calculated and difference in peritumoral and intra tumoral LVs was also assessed. A marked increase was seen we progressed from well-differentiated tumor to poorly differentiated ones, but this difference was found to be statistically nonsignificant. D2–40 immunostaining also highlighted the presence of lymphatic invasion present within the tumors which was detected by the presence of tumor emboli within the LVs. Overall, no significant correlation was found between D240 epithelial positivity and LVD.

Conclusion:

The expression of podoplanin in tumor cells and lymphatics when correlated with histopathological status and clinically with the lymph node status can definitely help in the adjuvant therapies used in OSCC.

Blood Vessel Invasion in Endometrial Cancer Is One of the Mechanisms of Spread to the Cervix

To evaluate the association between type of invaded vessels (blood or lymphatic) and cervical involvement in endometrial cancer (EC). Pathological slides of 93 patients with EC who had vascular space invasion in hematoxylin-eosin staining underwent immunohistochemical assay with CD31 and podoplanin. CD31 and podoplanin were used to identify blood and lymphatic invaded vessels, respectively. Cervical stromal invasion (CSI) was determined in 21 (30%) patients. The rate of CD31-positivity was significantly higher in patients with CSI than without (76.2 and 34.7%, p = 0.001; respectively). Podoplanin-positivity was determined in 47.6 and 81.6% of patients with and without CSI, respectively (p = 0.005). Age, myometrial invasion and the combination of CD31-positivity with podoplanin-negativity were found as independent predictors for CSI. Blood vessel invasion is an important factor for CSI in EC. Blood vessel invasion rather than lymphatic vessel invasion is one of the predominant ways by which EC spreads to the cervix.

The optimum marker for the detection of lymphatic vessels

Podoplanin, lymphatic vessel endothelial hyaluronic acid receptor-1, prospero-related homeobox-1 and vascular endothelial growth factor receptor 3 have been demonstrated to have crucial roles in the development of the lymphatic system and lymphangiogenesis process by combining with their corresponding receptors. Thus, the four markers have been widely used in labelling lymphatic vessels for the detection of lymphangiogenesis and lymphatic vessel invasion. Numerous authors have aimed to identify the roles of these four markers in the lymphatic system and the mechanisms have been partly clarified at the molecular level. The aim of the present review was to comprehensively clarify the characteristics and latent action modes of the four markers in order to determine which is the best one for the detection of lymphangiogenesis and lymphatic vessel invasion.

In silico pathway analysis in cervical carcinoma reveals potential new targets for treatment

An in silico pathway analysis was performed in order to improve current knowledge on the molecular drivers of cervical cancer and detect potential targets for treatment. Three publicly available Affymetrix gene expression data-sets (GSE5787, GSE7803, GSE9750) were retrieved, vouching for a total of 9 cervical cancer cell lines (CCCLs), 39 normal cervical samples, 7 CIN3 samples and 111 cervical cancer samples (CCSs). Predication analysis of microarrays was performed in the Affymetrix sets to identify cervical cancer biomarkers. To select cancer cell-specific genes the CCSs were compared to the CCCLs. Validated genes were submitted to a gene set enrichment analysis (GSEA) and Expression2Kinases (E2K). In the CCSs a total of 1,547 probe sets were identified that were overexpressed (FDR < 0.1). Comparing to CCCLs 560 probe sets (481 unique genes) had a cancer cell-specific expression profile, and 315 of these genes (65%) were validated. GSEA identified 5 cancer hallmarks enriched in CCSs (P < 0.01 and FDR < 0.25) showing that deregulation of the cell cycle is a major component of cervical cancer biology. E2K identified a protein-protein interaction (PPI) network of 162 nodes (including 20 drugable kinases) and 1626 edges. This PPI-network consists of 5 signaling modules associated with MYC signaling (Module 1), cell cycle deregulation (Module 2), TGFβ-signaling (Module 3), MAPK signaling (Module 4) and chromatin modeling (Module 5). Potential targets for treatment which could be identified were CDK1, CDK2, ABL1, ATM, AKT1, MAPK1, MAPK3 among others. The present study identified important driver pathways in cervical carcinogenesis which should be assessed for their potential therapeutic drugability.

M2-polarized tumor-associated macrophage infiltration of regional lymph nodes is associated with nodal lymphangiogenesis and occult nodal involvement in pN0 pancreatic cancer

OBJECTIVE

Tumor-associated macrophages (TAMs) are reportedly involved in lymphangiogenesis in primary tumors, playing a crucial role in lymphatic metastasis. Furthermore, nodal lymphangiogenesis precedes and promotes regional lymph node (RLN) metastasis. We investigated the relationship of M2-polarized TAM infiltration of the RLNs, nodal lymphangiogenesis, and occult nodal involvement in pN0 pancreatic cancer.

METHODS

Hematoxylin-eosin-stained primary tumor and regional LN specimens from 40 patients diagnosed with pN0 pancreatic cancer according to the pathological TNM classification were assessed. To evaluate lymphangiogenesis, lymphatic vessel density was measured by using D2-40 antibody. CD163 and cytokeratin AE1/AE3 antibodies were used to detect M2-polarized TAMs and isolated tumor cells in the RLNs, respectively.

RESULTS

The nodal lymphatic vessel density had a strong association with the M2-polarized TAM density in the RLNs (P < 0.0001). Most of these TAMs expressed vascular endothelial growth factor C. Furthermore, in the RLNs, the M2-polarized TAM density was significantly associated with the incidence of isolated tumor cells (P = 0.0477).

CONCLUSIONS

M2-polarized TAM infiltration of RLNs is significantly associated with nodal lymphangiogenesis and occult nodal involvement in pN0 pancreatic cancer. Node-infiltrating M2-polarized TAMs may facilitate nodal lymphangiogenesis via the production of vascular endothelial growth factor C and thus promote RLN metastasis.

[Prognostic value of lymphangiogenesis and lymphatic vessel invasion in non-small cell lung cancer]

BACKGROUND AND OBJECTIVE

Studies have shown that tumor metastasis in a variety of tumors is associated with lymphangiogenesis and lymphatic vessel invasion (LVI). Tumor metastasis is an important factor that affects the prognosis of patients. The aim of this study is to determine the prognostic value of lymphangiogenesis and LVI in non-small cell lung cancer (NSCLC).

METHODS

We marked the endothelial cells of lymph vessels in lymphangiogenesis with specific monoclonal antibody D2-40. Immunohistochemistry was used to detect the expression of lymphangiogenesis and LVI in 79 cases of stage I-III NSCLC.

RESULTS

The intratumoral lymphatic vessel density (ITLVD) was significantly higher in patients with N2 disease than those with N0 disease (P=0.015). The ITLVD was significantly higher in patients with LVI+ than that in those with LVI- (P = 0.009). The ITLVD was also remarkably higher in poorly differentiated tumors than that in highly differentiated ones (P = 0.007). The ITLVD was remarkably higher in adenocarcinoma than that in squamous cell carcinomas (P = 0.025). Kaplan-Meier revealed that the survival rates of patients with higher ITLVD were remarkably poorer than those with lower ITLVD (P = 0.007). Thus, the ITLVD is an important prognostic factor of NSCLC. The peritumoral lymphatic vessel density is not correlated with the prognosis.

CONCLUSIONS

The ITLVD level is an important prognostic factor of NSCLC.

Clinical significance of peritumoral lymphatic vessel density and lymphatic vessel invasion detected by D2-40 immunostaining in FIGO Ib1-IIa squamous cell cervical cancer

The clinical significance of lymphangiogenesis in cervical cancer remains controversial. Our aim was to investigate the correlation between lymphangiogenesis, lymphatic vessel invasion (LVI) and tumor metastasis, invasion and prognosis in squamous cell cervical cancer. Paraffin sections of 90 patients with FIGO (Fédération Internationale de Gynécologie et d'Obstétrique) Ib1-IIa squamous cell cervical cancer were stained for immunohistochemistry with a D2-40 monoclonal antibody against the carcinoembryonic antigen M2A. The lymphatic vessel density (LVD) and LVI were measured, and their relationship with the clinicopathological data was analyzed. D2-40-positive lymphatic vessels were found in 75 of the 90 patients (83.3 %). All D2-40-positive vessels were located in peritumoral areas. The mean±SD of the peritumoral LVD was 10.08±4.16. The positive rate of LVI was 32.0 % (24/75). The recurrence rate of patients with LVD >10 (62.1 %, 18/29) was significantly higher than that of patients with LVD ≤10 (34.8 %, 16/46, P = 0.021). The 5-year recurrence-free survival rate of patients with LVD >10 (41.0 %) was significantly lower than that of patients with LVD ≤10 (67.0 %, P = 0.045). Univariate analysis showed that the peritumoral LVD (≤10 vs >10) was correlated with LVI (absent vs present, P = 0.016). The peritumoral LVD and LVI showed no correlation with age, FIGO stage, tumor size, tumor grade, depth of invasion, or pelvic lymph node metastasis (all: P > 0.05). Peritumoral lymphangiogenesis was correlated with the recurrence and recurrence-free survival in patients with squamous cell cervical cancer. Examination of peritumoral LVD in these patients might therefore help to estimate the risk of recurrence.

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'.

Prognostic value of lymphangiogenesis in supraglottic laryngeal carcinoma

Background:

Metastasis to regional lymph nodes via lymphatic microvessels plays a key role in cancer progression, and is an important prognostic factor in many cancers. Recent evidence suggests that tumour lymphangiogenesis promotes lymphatic metastasis.

Aims:

To investigate whether tumour lymphatic microvessel density correlates with clinicopathological factors and serves as a prognostic indicator of supraglottic laryngeal carcinoma progression.

Methods:

The lymphatics of 84 supraglottic laryngeal carcinoma cases were investigated by immunohistochemical staining for podoplanin (also termed D2-40). The relationships between (intra- and peritumoural) lymphatic microvessel density, clinicopathological parameters and clinical prognosis were analysed.

Results:

There was a significant relationship between high intratumoural lymphatic microvessel density and aggressive tumour node stage (p < 0.0001), distant metastasis (p = 0.037) and poor prognosis (p = 0.011), and between high peritumoural lymphatic microvessel density and node stage (p = 0.004) and poor prognosis (p = 0.029). Patients with high lymphatic microvessel density also had significantly worse disease-free survival (p = 0.003) and overall survival (p = 0.005). Intratumoural lymphatic microvessel density was found to be an independent prognostic factor for overall survival (p = 0.008) and disease-free survival (p = 0.005) (multivariate analysis).

Conclusion:

Lymphatic microvessel density (detected by podoplanin immunohistochemistry), especially intratumoural density, may be an independent predictor of lymphatic tumour spread and survival in supraglottic laryngeal carcinoma patients, and may be useful to guide decisions regarding additional surgery.

M2-polarized tumor-associated macrophages are associated with poor prognoses resulting from accelerated lymphangiogenesis in lung adenocarcinoma

OBJECTIVES

Tumor-associated macrophages have been implicated in promoting tumor growth, progression and metastasis. However, the activated phenotype (M1 or M2) of tumor-associated macrophages remains unknown in solid tumors. Therefore, this study examined the density and prognostic significance of M2-polarized tumor-associated macrophages in lung adenocarcinoma.

METHODS

Tumor specimens from 65 lung adenocarcinoma patients were assessed by ELISA for Th1/Th2 cytokine concentrations. The activated phenotype (M1 or M2) of tumor-associated macrophages was determined utilizing immunofluorescence staining. Additionally, to evaluate lymphangiogenesis, peritumoral lymphatic microvessel density was measured using D2-40. The correlation between tumor-associated macrophage subtype and overall patient survival was analyzed using the Kaplan-Meier method and compared using the log-rank test.

RESULTS

A shift toward Th2 cytokine expression was detected within lung adenocarcinoma microenvironments. Approximately 79.71±16.27% of tumor-associated macrophages were M2 polarized; the remaining 20.35±5.31% were M1 polarized. The infiltration of M2-polarized macrophages was significantly associated with P-TNM staging and lymph node metastasis. The peritumoral lymphatic microvessel density was significantly higher in the high M2-polarized tumor-associated macrophage group than in the low M2-polarized tumor-associated macrophage group. A significant difference in overall patient survival was detected not only between patients with tumors with high and low macrophage counts but also between patients with tumors with high and low counts of M2-polarized macrophages.

CONCLUSION

Tumor-associated macrophages in lung adenocarcinoma have an M2-polarized subtype and are associated with poor prognoses, perhaps resulting from accelerated lymphangiogenesis and lymph node metastasis.

Association between intratumoral lymphatic microvessel density (LMVD) and clinicopathologic features in endometrial cancer: a retrospective cohort study

BACKGROUND

Lymph node metastasis in endometrial cancer significantly decreases survival rate. Few data on the influence of intratumoral lymphatic microvessel density (LMVD) on survival in endometrial cancer are available. Our aim was to assess the intratumoral LMVD of endometrial carcinomas and to investigate its association with classical pathological factors, lymph node metastasis and survival.

METHODS

Fifty-seven patients with endometrial carcinoma diagnosed between 2000 and 2008 underwent complete surgical staging and evaluation of intratumoral LMVD and other histologic variables. Lymphatic microvessels were identified by immunohistochemical staining using monoclonal antibody against human podoplanin (clone D2-40) and evaluated by counting the number of immunostained lymphatic vessels in 10 hot spot areas at 400× magnification. The LMVD was expressed by the mean number of vessels in these 10 hot spot microscopic fields. We next investigated the association of LMVD with the clinicopathologic findings and prognosis.

RESULTS

The mean number of lymphatic vessels counted in all cases ranged between 0 and 4.7. The median value of mean LMVD was 0.5, and defined the cut-off for low and high LMVD. We identified low intratumoral LMVD in 27 (47.4%) patients and high LMVD in 30 (52.6%) patients. High intratumoral LMVD was associated with lesser miometrial and adnaexal infiltration, lesser cervical and peritoneal involvement, and fewer fatal cases. Although there was lower lymph node involvement among cases with high LMVD, the difference did not reach significance. No association was seen between LMVD and FIGO staging, histological type, or vascular invasion. On the other hand, low intratumoral LMVD was associated with poor outcome. Seventy-five percent of deaths occurred in patients with low intratumoral LMVD.

CONCLUSION

Our results show association of high intratumoral LMVD with features related to more localized disease and better outcome. We discuss the role of lymphangiogenesis as an early event in the endometrial carcinogenesis.

Stromal issues in cervical cancer: a review of the role and function of basement membrane, stroma, immune response and angiogenesis in cervical cancer development

The carcinogenesis of cervical carcinoma implies an intricate interplay of neoplastic, human papillomavirus infected epithelial cells and stromal tissue, in which different factors have distinct but interacting influence. Persistent infection with an oncogenic human papillomavirus type may lead to epithelial dysplasia with progressive severity. To access the adjacent stromal tissue, tumour cells have to breach the basement membrane. The stroma partly controls tumour growth, invasion and angiogenesis. Last but not least there is considerable influence of the immune response. In this review we describe the importance of various stromal factors in carcinogenesis of cervical cancer.

Significance of periductal lymphatic and blood vascular densities in intraductal carcinoma of the breast

We investigated the significance of periductal lymphatic and blood vascular densities in intraductal carcinomas (IDC) of the breast. Thirty five cases of pure IDC treated by partial or total mastectomy were reviewed. Seven cases with normal breast tissue and 48 cases of invasive breast carcinoma were included as controls. All cases were immunostained with D2-40 and CD31. Positively stained microvessels were counted in densely vascular/lymphatic foci (hot spots) at 400x (=0.17 mm(2)) in the periductal areas. IDC without comedonecrosis showed a mean periductal D2-40 lymphatic microvessel density (LMD) of 5.8 +/- 5 (range 0-18), and a CD31 microvessel density (MD) of 14 +/- 8.9 (range 1-40). IDC with comedonecrosis showed periductal D2-40 LMD of 8.4 +/- 3.8 (range 4-18), and a CD31 MD of 24.3 +/- 7.6 (range 14-40). There was a significant difference between periductal D2-40 LMD and CD31 MD counts in IDC with and without comedonecrosis. There was a positive correlation of periductal D2-40 LMD and CD31 MD counts with high nuclear grade (r = 0.39 and 0.56) of IDC as well as with the presence of comedonecrosis (r = 0.49 and 0.59). Both D2-40 LMD and CD31 MD did not correlate significantly with tumor size, estrogen status, or progesterone status. As IDC with comedonecrosis and/or high nuclear grade has a worse prognosis than IDC without comedonecrosis and/or with low nuclear grade, it appears that lymphatic and blood vascular density evaluated by D2-40 and CD31, respectively, are independent prognostic indicators for patients with IDC of the breast and may be an indicator of early or unrecognized invasion or "regression."

Significance of M2-polarized tumor-associated macrophage in pancreatic cancer

BACKGROUND

The roles of infiltrating macrophages within the tumor microenvironment are complex because of their functional variety. The aim of this study is to examine the role and prognostic significance of tumor-associated macrophages (TAMs) that have an M2 polarized function in pancreatic cancer.

MATERIALS AND METHODS

Formalin-fixed, paraffin-embedded blocks were obtained from 76 patients with pancreatic head cancer. All patients underwent macroscopic curative resection. We assessed the number of infiltrating macrophages within the tumor invasive front by not only CD68 but also by CD163 and CD204, which are specific receptors on M2-polarized macrophages. Furthermore, to evaluate lymphangiogenesis, we measured the density of lymphatic vessels in the tumor invasive front by using D2-40.

RESULTS

High incidence of lymph node metastasis was shown in cases with a high number of CD163- or CD204-positive macrophages. Significantly increased lymphatic vessel density (LVD) was shown in cases with lymph node metastasis compared with cases without lymph node metastasis (P=0.0094). Significantly increased LVD (P=0.0175) and a poor prognosis (P=0.0171) were shown in cases with a high number of macrophages that express CD163 or CD204, however, there was no significant difference according to the number of CD68-positive macrophages.

CONCLUSIONS

M2-polarized TAMs in the invasive front of pancreatic cancer are associated with a poor prognosis due to accelerated lymphatic metastasis, and inhibition of the functional interaction between M2-polarized TAMs and tumor cells may improve the prognosis.

Increased lymphatic vascular density is seen before colorectal cancers reach stage II and growth factor FGF-2 is downregulated in tumor tissue compared with normal mucosa

Lymphangiogenesis is an important event in progression of colorectal cancer (CRC), and the estimated lymphatic vascular density (LVD) probably indicates facilitated lymphatic tumor cell invasion and metastasis. However, at what time point during tumor progression this process is triggered, is unclear. The aim of this study was twofold. Firstly, to examine LVD in paired samples of CRC tissue and normal mucosa with specific emphasis on possible difference in LVD between tumors stages II and III, and secondly, the expression of the lymphangiogenic growth factor fibroblast growth factor-2 (FGF-2). Eighteen patients were studied. Immunostaining for podoplanin was performed to highlight lymphatic vessels. FGF-2 mRNA expression was determined by quantitative real-time RT-PCR, whereas protein expression was quantitatively assessed by densitometric analysis of Western blot signal intensity. The immunoblots were further validated by FGF-2 immunostaining of histological sections. LVD was significantly increased in tumor tissue compared with the normal mucosa but no changes in LVD between stages II and III CRC was observed. FGF-2 was found to be downregulated both at the mRNA and protein level in tumor tissues compared with normal mucosa. Lymphangiogenesis was triggered early in tumor development. An increased LVD was established before the tumor reached stage II. FGF-2 was downregulated in tumor tissue. The importance of this finding remains unclear.

Intratumoral lymphangiogenesis of esophageal squamous cell carcinoma and relationship with regulatory factors and prognosis

The clinical and pathological significance of intratumoral lymphangiogenesis (ITL) with human esophageal squamous cell carcinomas (ESCC) remains unclear, as does the role of signaling molecules such as vascular endothelial growth factor (VEGF)-A,C, platelet-derived growth factor (PDGF)-A, and p53, in the regulation of ITL. Lymphatic vessel density (LVD) was significantly increased in VEGF-A and VEGF-C immunohistochemical score 1 and 2-3 groups as compared to the score 0 group and also with high of VEGF-A, VEGF-C and PDGF-A mRNA expression. Both LVD and blood vessel density (BVD) were significantly greater in the p53 gene mutant group than in the wild-type group. Lymph node metastasis was significantly more frequent with than without ITL and Kaplan-Meier analysis indicated a significantly poorer prognosis. Multivariate analysis using Cox proportional hazard method showed that invasion depth, lymph node metastasis and ITL were independent prognostic factors.

Lymphangiogenesis induced by VEGF-C and VEGF-D promotes metastasis and a poor outcome in breast carcinoma: a retrospective study of 61 cases

PURPOSE

To evaluate lymphangiogenesis in patients with breast carcinoma, explore the underlying mechanism, and study the relationship between lymphangiogenesis and progression of breast carcinoma.

METHODS

Sixty-one cases of breast carcinoma with complete clinical and pathological data were analyzed. Using an anti-podoplanin monoclonal antibody, an immunohistochemical study was made of all specimens to detect lymphatic vessel density (LVD) and to investigate its clinicopathological and prognostic value. VEGF-C and VEGF-D were observed by RT-PCR and immunostaining to investigate their clinicopathological and prognostic values and their relationship with lymphangiogenesis.

RESULTS

LVD in breast carcinoma (6.28+/-3.73) was significantly higher than in benign mammary lesions (0.50+/-1.27), P<0.01 and was significantly associated with lymphatic metastasis and high TNM stage, P<0.01. The level of VEGF-C and VEGF-D expression was also significantly higher in breast carcinomas than in benign mammary lesions, P<0.01. LVD increased significantly with higher expression of VEGF-C and VEGF-D, P<0.01. Patients with high expression of VEGF-C and VEGF-D were observed to be more likely to have a bad outcome, P<0.05.

CONCLUSIONS

Lymphangiogenesis was significantly associated with lymph node metastasis, high TNM, and poor outcome in breast carcinoma. LVD may serve as a predictor of lymph node metastasis and a prognostic factor in breast carcinoma. VEGF-C and VEGF-D play an important role in lymphangiogenesis making the carcinoma more aggressive and leading to a poor prognosis.

Role of lymphangiogenesis in cancer

Regional lymph node metastasis is a common event in solid tumors and is considered a marker for dissemination, increased stage, and worse prognosis. Despite rapid advances in tumor biology, the molecular processes that underpin lymphatic invasion and lymph node metastasis remain poorly understood. However, exciting discoveries have been made in the field of lymphangiogenesis in recent years. The identification of vascular endothelial growth factor ligands and cognate receptors involved in lymphangiogenesis, an understanding of the embryology of the mammalian lymphatic system, the recent isolation of pure populations of lymphatic endothelial cells, the investigation of lymphatic metastases in animal models, and the identification of markers that discriminate lymphatics from blood vessels at immunohistochemistry are current advances in the field of lymphangiogenesis, and as such are the main focus of this article. This review also evaluates evidence for lymphangiogenesis (ie, new lymphatic vessel formation in cancer) and critically reviews current data on the prognostic significance of lymphatic vascular density in tumors. A targeted approach to block pathways of lymphangiogenesis seems to be an attractive anticancer treatment strategy. Conversely, promotion of lymphangiogenesis may be a promising approach to the management of treatment-induced lymphedema in cancer survivors. Finally, the implications of these developments in cancer therapeutics and directions for future research are discussed.

DNA demethylation of vascular endothelial growth factor-C is associated with gene expression and its possible involvement of lymphangiogenesis in gastric cancer

Previous studies have indicated that lymphangiogenesis in solid tumors is associated with lymphatic metastasis. Overexpression of Vascular endothelial growth factor (VEGF)-C plays a major role in lymphangiogenesis in cancers. In the present study, DNA methylation and expression of the VEGF-C gene was investigated in gastric cancer (GC). Four GC cell lines (MKN-45, MKN-74, HSC-39 and HSC-43) showed no expression of VEGF-C, and the VEGF-C gene was found to be methylated in these cells. In contrast, 7 GC cell lines (MKN-1, MKN-7, MKN-28, TMK-1, KATO-III, SH101-P4 and HSC-44PE) expressed VEGF-C, and the VEGF-C gene was found to be unmethylated in these cell lines. In addition, expression of VEGF-C mRNA was retrieved by treatment with a demethylating agent, Aza-2'-deoxycytidine. In GC tissue samples, bisulfite DNA sequencing analysis revealed that VEGF-C was not methylated in 9 (29.0%) of 31 GC samples, whereas demethylation was not observed in corresponding non-neoplastic mucosa samples. Overexpression of VEGF-C mRNA was observed in 16 (51.6%) of 31 GC samples by quantitative reverse transcription-polymerase chain reaction. Of the 9 GC cases with VEGF-C demethylation, 8 (88.9%) overexpressed VEGF-C. In contrast, of the 22 GC cases without VEGF-C demethylation, 8 (36.4%) overexpressed VEGF-C (p = 0.0155). Furthermore, lymphatic vessel density determined by immunostaining of podoplanin in GC tissues was associated with overexpression of VEGF-C (p < 0.0001). These results suggest that demethylation and activation of the VEGF-C gene is likely involved in lymphangiogenesis in GC.

Lymphatic endothelial cells, tumor lymphangiogenesis and metastasis: New insights into intratumoral and peritumoral lymphatics

Lymphatic metastasis of tumor cells represents a series of extremely complex and sequential processes that include dissemination and invasion into surrounding stromal tissues from primary tumors, penetration into lymphatic walls and implantation in regional lymph nodes, and extravasation or proliferation in parenchyma of target organs. Recent developments in lymphatic biology and research, especially the application of unique molecular markers specific for lymphatic endothelial cells (LECs), LYVE-1, Prox-1 and podoplanin have provided exciting new insights into the tumor microenvironment and LEC-tumor cell interface. To date, established factors for determining the behavior and prognosis of primary tumors have been emphasized morphologically and physiologically, i.e., lymphatic impairment and vessel density, dysfunction of lymphatic valves, interstitial fluid pressure, as well as a series of lymphangiogenic growth factors including VEGF-C/-D, and other cytokines and chemokines. Increasing knowledge of the tumor biological significance in lymphatics within the tumors (intratumoral lymphatics, ITLs) and at the tumor periphery (peritumoral lymphatics, PTLs) has greatly promoted understanding of tumor access into the lymphatic system by inducing lymphangiogenesis or by co-opting preexisting lymphatics. Therefore, the targeting PTLs and ITLs, which have been proposed as an important route for antimetastatic approach, are deemed worthy of further study in various animal tumor models and human tumors.

Diagnostic utility of D2-40 and podoplanin in effusion cell blocks

The distinction between malignant mesothelioma and adenocarcinoma is a diagnostic challenge in cytologic specimens of effusion fluids. As for today, no single antibody has demonstrated absolute sensitivity or specificity for Mesothelioma. D2-40 and podoplanin have recently been recognized to stain mesothelial cells. Our aim for this study was to evaluate the utility of these two markers as indicators of mesothelial cells using cell blocks by comparison with two other established mesothelial markers. A total of 40 cell blocks of effusion fluids including cases of epithelioid mesotheliomas, metastatic carcinomas and benign cases with reactive mesothelial cells were selected. A panel of immunostains including D2-40, podoplanin, CK5, and calretinin was performed. D2-40 and podoplanin were positive in 100% of mesothelioma cases in comparison to metastatic adenocarcinoma cases where the positivity was 0%. It is concluded that D2-40 and podoplanin are very useful markers for mesotheliomas. Since these markers are extremely helpful in differentiating epithelioid mesothelioma from metastatic adenocarcinoma, they shall be a valuable addition to the battery of markers used to differentiate the two entities.

First international consensus on the methodology of lymphangiogenesis quantification in solid human tumours

The lymphatic system is the primary pathway of metastasis for most human cancers. Recent research efforts in studying lymphangiogenesis have suggested the existence of a relationship between lymphatic vessel density and patient survival. However, current methodology of lymphangiogenesis quantification is still characterised by high intra- and interobserver variability. For the amount of lymphatic vessels in a tumour to be a clinically useful parameter, a reliable quantification technique needs to be developed. With this consensus report, we therefore would like to initiate discussion on the standardisation of the immunohistochemical method for lymphangiogenesis assessment.

Intratumoral Lymphatic Vessels and VEGF-C Expression Are Predictive Factors of Lymph Node Relapse in T1-T4 N0 Laryngopharyngeal Squamous Cell Carcinoma

BACKGROUND

The presence of intratumoral lymphatic vessels (ILVs) and the expression of vascular endothelial growth factor-C (VEGF-C) in tumour cells have been studied as markers of lymphangiogenesis in order to evaluate their role in metastatic dissemination in laryngopharyngeal squamous cell carcinoma.

METHODS

A retrospective study was performed in 76 patients of N0 laryngopharyngeal carcinoma. with variable tumour size (T1-T4), histological grade, and location (supraglottic, glottic and hypopharyngeal). The presence of ILVs, as revealed by the expression of PA2.26 antigen and VEGF-C expression, were determined by immunohistochemistry (IHC). Low-grade and high-grade lymphangiogenesis were defined by qualitative and quantitative criteria.

RESULTS

Multivariate analysis revealed low-grade ILV and VEGF-C expression to be associated respectively with 30.3- and 16.2-fold higher probabilities of cervical lymph node relapse (P = 0.005 and P = 0.032) and with 16.2- and 8.44-fold shorter disease-free survival (P = 0.009 and P = 0.045).

CONCLUSIONS

Low-grade ILV and VEGF-C expression are independent predictive factors of cervical lymph node relapse and shortening of time to relapse in N0 laryngopharyngeal carcinoma.

Lymphatic microvessel density as prognostic marker in colorectal cancer

Lymph node metastases is an important prognostic indicator for disease progression and crucial for therapeutic strategies in the work-up of colorectal carcinoma. In this study, we investigated tumor lymphangiogenesis and vascular endothelial growth factor (VEGF) expression as predictive markers for the risk of lymph node metastasis and their relation to other prognostic parameters in colorectal carcinoma. Resected colorectal carcinomas from 90 patients were examined, including 30 patients without lymph node metastases, 30 with only lymph node metastases, and 30 with liver metastases. Cases were immunostained for CD31, D2-40, and VEGF. Positivity stained microvessels were counted in densely vascular/lymphatic foci (hot spots) at x 400 field (=0.17 mm2). Intensity of staining for VEGF was scored on a two-tiered scale. D2-40 lymphatic microvessel density demonstrated significant correlation with CD31 counts (20+/-9 vs 18+/-6/0.17 mm2 field, P<0.05) and VEGF expression (P<0.01). VEGF was expressed in 61/90 (67%) cases. D2-40 identified lymphatic tumor invasion in 48/90 patients, which was greater than CD31 (37/90) and hematoxylin and eosin (H&E) (31/90). There was a positive significant correlation of D2-40, CD31 counts, and VEGF expression with the presence of lymphovascular invasion and lymph node metastases (P<0.05). D2-40 lymphatic microvessel density correlated significantly with depth of invasion (pT), positive vascular pedicle lymph nodes and liver metastases (P<0.05). In conclusion, D2-40 lymphatic microvessel density showed prognostic significance with positive correlation with lymphovascular invasion, pT, and metastases to lymph nodes and liver. Immunostaining with D2-40 enhances the detection of lymphatic invasion relative to H&E staining and the endothelial marker, CD31.

Tumour lymphangiogenesis is a possible predictor of sentinel lymph node status in cutaneous melanoma: a case-control study

BACKGROUND

Cutaneous melanoma spreads preferentially through the lymphatic route and sentinel lymph node (SLN) status is regarded as the most important predictor of survival.

AIMS

To evaluate whether tumour lymphangiogenesis and the expression of vascular endothelial growth factor C (VEGF-C) is related to the risk of SLN metastasis and to clinical outcome in a case-control series of patients with melanoma.

METHODS

Forty five invasive melanoma specimens (15 cases and 30 matched controls) were investigated by immunostaining for the lymphatic endothelial marker D2-40 and for VEGF-C. Lymphangiogenesis was measured using computer assisted morphometric analysis.

RESULTS

Peritumorous lymphatic vessels were more numerous, had larger average size, and greater relative area than intratumorous lymphatics. The number and area of peritumorous and intratumorous lymphatics was significantly higher in melanomas associated with SLN metastasis than in non-metastatic melanomas. No significant difference in VEGF-C expression by neoplastic cells was shown between metastatic and non-metastatic melanomas. Using logistic regression analysis, intratumorous lymphatic vessel (LV) area was the most significant predictor of SLN metastasis (p = 0.04). Using multivariate analysis, peritumorous LV density was an independent variable affecting overall survival, whereas the intratumorous LV area approached significance (p = 0.07).

CONCLUSIONS

This study provides evidence that the presence of high peritumorous and intratumorous lymphatic microvessel density is associated with SLN metastasis and shorter survival. The intratumorous lymphatic vessel area is the most significant factor predicting SLN metastasis. The tumour associated lymphatic network constitutes a potential criterion in the selection of high risk patients for complementary treatment and a new target for antimelanoma therapeutic strategies.

Lymphangiogenesis does not occur in breast cancer

Breast cancer metastasis predominantly occurs via lymphatic vessels. However, the study of lymphatic vessels and lymphangiogenesis has been hampered by lack of specific markers. Recently, antibodies directed against M2A (D2-40), Podoplanin, and Prox-1 that specifically mark lymphatic vessels in paraffin-embedded sections have become available. These were used to study lymphangiogenesis in archival paraffin sections of normal breast (n = 23), fibrocystic disease (n = 7), ductal carcinoma in situ (n = 32), invasive ductal carcinoma (n = 50), and invasive lobular carcinoma (n = 5). In addition, endothelial proliferation in lymphatic vessels was analyzed by dual-color immunohistochemistry with D2-40 and proliferating cell nuclear antigen (PCNA). Expression of D2-40, Prox-1, and Podoplanin was seen in lymphatic vessels but not in blood vessels. Lymphatic vessels were seen in the peritumoral area and as "entrapped" intratumoral vessels adjacent to preexisting normal lobules and ducts. Unlike angiogenesis, there was no increase of lymphatic vessel density in association with neoplastic transformation. On the contrary, a marked reduction in intratumoral lymphatic vessel density was seen in comparison to normal breast tissue, fibrocystic disease, and ductal carcinoma in situ (P = 0.0001). There was an increase in peritumoral lymphatic vessel density as compared with normal breast (P = 0.0001). However, the endothelial cells in the "entrapped" or the peritumoral lymphatic vessels did not show any expression of PCNA indicating minimal or no proliferative activity. This was in contrast to the strong expression seen in adjacent tumor cells and blood vessel endothelial cells. Thus, lymphangiogenesis was not evident when studied by lymphatic vessel density or by lymph vessel endothelial proliferation.

Peritumoral lymphatic vessel density and vascular endothelial growth factor C expression in early-stage squamous cell carcinoma of the uterine cervix

PURPOSE

Lymphatic invasion and nodal metastasis plays a major role in the spread of cervical cancer; however, little is known about the mechanisms whereby tumor cells enter the lymphatic system.

EXPERIMENTAL DESIGN

We examined the intra- and peritumoral lymphatic vessel density (LVD) using D2-40 immunohistochemistry in 111 cervical squamous cell carcinomas and correlated them with vascular endothelial growth factor (VEGF)-C expression, clinicopathologic tumor features, and outcome.

RESULTS

Compared with benign cervix, intratumoral and peritumoral LVD was significantly increased (P < 0.0001). Peritumoral LVD was significantly higher than intratumoral LVD (P = 0.009). High peritumoral, but not intratumoral, LVD showed significant correlation with high tumor stage, lymphatic invasion, and nodal metastasis. VEGF-C showed increased expression at the invasive edge compared with the center of tumors (P < 0.0001) and correlated with high peritumoral LVD, lymphatic invasion, and nodal metastasis. High peritumoral LVD and VEGF-C expression at the invasive edge of tumors were associated with poor overall and recurrence-free survival in univariate analysis. In multivariate analysis, peritumoral LVD was the only independent term predictive of overall survival.

CONCLUSIONS

Our findings suggest a potential role for VEGF-C in tumor-induced lymphangiogenesis represented by high peritumoral LVD, which may be one of the mechanisms leading to lymphatic invasion and metastatic spread. High peritumoral LVD may be an independent prognostic factor in early-stage cervical cancer.

The diagnostic utility of immunohistochemistry and electron microscopy in distinguishing between peritoneal mesotheliomas and serous carcinomas: a comparative study

The histologic distinction between peritoneal epithelioid mesotheliomas and serous carcinomas diffusely involving the peritoneum may be difficult, but it can be facilitated by the use of immunohistochemistry and electron microscopy. D2-40 and podoplanin are two recently recognized lymphatic endothelial markers that can be expressed in normal mesothelial cells and mesotheliomas. The purpose of this study is to compare the value of these new mesothelial markers with those that are commonly used for discriminating between mesotheliomas and serous carcinomas, and also to determine the current role of electron microscopy in distinguishing between these malignancies. A total of 40 peritoneal epithelioid mesotheliomas and 45 serous carcinomas of the ovary (15 primary, 30 metastatic to the peritoneum) were investigated for the expression of the following markers: D2-40, podoplanin, calretinin, keratin 5/6, thrombomodulin, MOC-31, Ber-EP4, B72.3 (TAG-72), BG-8 (Lewis(Y)), CA19-9, and leu-M1 (CD15). All 40 (100%) of the mesotheliomas reacted for calretinin, 93% for D2-40, 93% for podoplanin, 93% for keratin 5/6, 73% for thrombomodulin, 13% for Ber-EP4, 5% for MOC-31, 3% for BG-8, and none for B72.3, CA19-9, or leu-M1. All 45 (100%) serous carcinomas were positive for Ber-EP4, 98% for MOC-31, 73% for B72.3, 73% for BG-8, 67% for CA19-9, 58% for leu-M1, 31% for keratin 5/6, 31% for calretinin, 13% for D2-40, 13% for podoplanin, and 4% for thrombomodulin. After analyzing the results, it is concluded that Ber-EP4 and MOC-31 are the best negative mesothelioma markers for differentiating between epithelioid mesotheliomas and serous carcinomas. The best discriminators among the positive markers for mesotheliomas are D2-40, podoplanin, and calretinin. From a practical point of view, Ber-EP4 and MOC-31, in combination with calretinin, and/or D2-40 or podoplanin allow the differential diagnosis to be established between mesothelioma and serous carcinoma in nearly all instances. As a clear distinction could be made between these two malignancies in all of the cases in which electron microscopy was performed, this technique can be very useful in establishing the correct diagnosis when the immunohistochemical results are equivocal or further support of a diagnosis of either mesothelioma or serous carcinoma is needed.

Importance of lymph vessels in gastric cancer: a prognostic indicator in general and a predictor for lymph node metastasis in early stage cancer

BACKGROUND

Metastasis to regional lymph nodes (LNs) through lymphatic vessels is common in cancer progression and is an important prognostic factor in many cancers. Recent evidence suggests that tumour lymphangiogenesis promotes lymphatic metastasis.

AIMS

To study the role of lymph vessel density (LVD) in gastric cancer and investigate whether LVD is associated with LN metastasis/prognosis.

METHODS

Lymphatics of 117 primary human gastric cancer cases were investigated by quantitative immunohistochemical staining for podoplanin. The relation between LVD and LN metastasis and other established clinicopathological parameters was analysed. The relation between LVD and prognosis was also studied.

RESULTS

Mean LVD of "hot spots" was 11.6/case. LVD significantly correlated with LN and podoplanin positive lymphatic invasion. High LVD was associated with worse overall survival. In multivariate analysis, positive LVD was a significant independent predictor of overall survival, depth of invasion, and TNM stage. LVD significantly correlated with LN metastasis at surgery and podoplanin positive lymphatic invasion. In multivariate analysis, positive LVD was an independent significant predictor of LN metastasis.

CONCLUSIONS

Increased podoplanin expression is significantly associated with LN metastasis, and may play an important role in detecting LN metastasis in gastric cancer. Furthermore, LVD may be a significant prognostic factor in gastric cancer at any stage. In addition, LVD and lymph vessel invasion detected by podoplanin immunohistochemistry are associated with LN metastasis in T1 early gastric cancer. LVD assessment by podoplanin immunohistochemistry may become a useful predictor of LN metastasis in T1 early gastric cancer and may influence the decision making process for additional surgery.

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.

Lymphatic vessel density and lymph node metastasis in prostate cancer

BACKGROUND

Few data are available examining the significance of prostatic lymphatic vessel density (LVD) to lymph node metastasis in patients with prostate cancer. The purpose of this study was to determine the distribution of lymphatic vessels in non-carcinomatous prostate tissue, and investigate the relationship between LVD and lymph node status in prostate cancer.

METHODS

LVD, identified by D2-40 immunostaining, was evaluated in non-carcinomatous prostates (n = 7) and prostate cancer (n = 37). The staining pattern of D2-40 was compared with that of another lymphatic vessel marker, vascular endothelial growth factor (VEGF) receptor-3, and a blood vessel endothelial marker, CD34, in adjacent sections.

RESULTS

The D2-40 antigen, podoplanin, was expressed exclusively in lymphatic vessels within tumor and normal tissue in all specimens. There was no overlap between cell staining for D2-40 and CD34. Peritumoral LVD and peritumoral lymphatic invasion were significantly associated with lymph node metastasis. VEGF receptor-3 was expressed in a subset of D2-40+ lymphatic vessels.

CONCLUSIONS

We have demonstrated that peritumoral lymphatic vessels are likely to serve as major conduits for nodal metastasis in prostate cancer using D2-40 to decorate lymphatic endothelium marker podoplanin. Lack of coexpression of podoplanin and VEGF receptor-3 in some lymphatic vessels suggests the heterogeneity of lymphatic endothelial cells in prostate tissue.

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.

VEGF-D expression and lymph vessels play an important role for lymph node metastasis in papillary thyroid carcinoma

Papillary thyroid carcinoma frequently metastasizes to regional lymph nodes, and lymph node metastasis increases the risk of local regional relapse. Recent evidence suggests that vascular endothelial growth factor-D (VEGF-D) promotes lymphangiogenesis, which in turn promotes lymphatic metastasis. Therefore, the role of VEGF-D messenger RNA transcript levels and VEGF-D immunoreactivity in lymph node metastasis in papillary thyroid carcinoma was investigated. In addition, the role of blood vascular vessel, lymph vessel, and Flt-4-positive vessel densities were studied in relation to their suspected association with lymph node metastasis, and with VEGF-D expression. VEGF-D messenger RNA transcript levels by quantitative real-time reverse transcription-polymerase chain reaction and VEGF-D immunoreactivity by immunohistochemistry in 49 papillary thyroid carcinomas were also studied. This was followed by quantitative immunohistochemical staining for CD34, podoplanin, and Flt-4. Lymph node metastasis was significantly correlated with VEGF-D messenger RNA transcript levels (P=0.027) and VEGF-D immunoreactivity (P=0.019). Increased lymph vessel density was also correlated with VEGF-D expression and lymph node metastasis. In conclusion, our findings indicate that VEGF-D expression and increased lymph vessel density may have an important role for lymph node metastasis in papillary thyroid carcinoma.

Lymph vessel density correlates with nodal status, VEGF-C expression, and prognosis in breast cancer

Metastasis to the regional lymph nodes through the lymphatic vessels is a common step in the progression of cancer and an important prognostic factor in many types of cancer. Recent evidence suggests that VEGF-C promotes lymphangiogenesis, and that tumor lymphangiogenesis in turn promotes lymphatic metastasis. We have studied the role of LVD in breast cancer, and examined whether LVD is associated with lymph node metastasis, VEGF-C expression, or prognosis. In addition, we examined whether VEGF-C mRNA transcript levels were associated with lymph node metastasis and LVD. We began by investigating the lymphatics in primary human breast carcinoma with long-term follow-up (113 cases of invasive ductal and other breast cancers) by quantitative immunohistochemical staining for podoplanin. We then analyzed the relationship between LVD and lymph node status as well as VEGF-C immunoreactivity and other established clinicopathological parameters. The relationship between LVD and prognosis was also studied. VEGF-C mRNA transcript levels were examined by quantitative real-time RT-PCR, in 55 invasive ductal breast carcinomas. This was followed by an analysis of the relationship between VEGF-C mRNA transcript levels and lymph node metastasis as well as LVD. Mean LVD of 'hot spots' was 10.2 +/- 7.4/each case. LVD was significantly correlated with lymph node metastasis (p < 0.0001), VEGF-C immunoreactivity (p = 0.0084), and podoplanin positive lymphatic invasion (p < 0.0001). Survival curves determined by the Kaplan-Meier method and univariate analysis demonstrated that high LVD was associated with both worse disease free survival (p = 0.0033) and overall survival (p = 0.0391). VEGF-C mRNA transcript levels were also correlated with lymph node metastasis (p = 0.0074) and LVD (p = 0.0409). Increased LVD was correlated with lymph node metastasis and VEGF-C expression. High LVD may be a significant unfavorable prognostic factor for long-term survival in breast cancer.

Podoplanin as a marker for mesothelioma

Podoplanin is a specific marker for lymph vessel endothelial cells. It was noted that podoplanin is expressed in reactive mesothelial cells. The utility of podoplanin for the histological diagnosis of tumors was then investigated, especially for mesothelioma. Immunohistochemical study of podoplanin was carried out in five malignant mesotheliomas and 118 other tumors including 93 adenocarcinomas, four squamous cell carcinomas, six gastrointestinal stromal tumors and five endocrine tumors. Immunoreactivity for podoplanin was demonstrated on the cell membrane of tumor cells for all mesotheliomas. All other tumors were negative for podoplanin. Among the many antibodies used for differential diagnosis of malignant mesothelioma, podoplanin has the potential to be an excellent tumor marker in both specificity and sensitivity. The utility of podoplanin as a marker for mesothelioma will be confirmed by further studies.

Lack of lymphangiogenesis during breast carcinogenesis

BACKGROUND

Recent evidence suggests that functional intratumorous lymph vessels may be absent from some human cancers. This could result from either the failure of tumours to induce lymphangiogenesis, or the collapse of lymph vessels, caused by high interstitial tumour pressure.

METHODS

To differentiate between these two hypotheses, paraffin wax embedded clinical specimens from normal breast (n = 13), usual ductal hyperplasia (n = 11), ductal carcinoma in situ (n = 21), and invasive breast cancer (n = 40) were compared for lymphatic and blood vessel density by immunohistochemistry with antibodies to the lymphatic endothelial hyaluronan receptor (LYVE-1) and CD31, respectively.

RESULTS

Lymph vessel density was lower than blood vessel density in normal breast tissue. Within breast lobuli, lymph vessels were absent. In premalignant lesions blood microvessel density increased, whereas no increase in lymph vessels could be seen intralesionally. In invasive cancers, lymph vessels were absent in all but a few cases, where probably some pre-existing lymph vessels remained, although blood microvessel density was once again increased.

CONCLUSION

Unlike angiogenesis, lymphangiogenesis is absent during breast carcinogenesis. This, and not rising interstitial pressure caused by an increase in the size of lesions, explains the absence of intratumorous lymph vessels in invasive breast cancer.

Lymphatic density and metastatic spread in human malignant melanoma

Malignant melanoma (MM), the most common cause of skin cancer deaths, metastasises to regional lymph nodes. In animal models of other cancers, lymphatic growth is associated with metastasis. To assess if lymphatic density (LD) was increased in human MM, and its association with metastasis, we measured LD inside and around archival MM samples (MM, n=21), and compared them with normal dermis (n=11), basal cell carcinoma (BCC, n=6) and Merkel cell carcinoma (MCC), a skin tumour thought to metastasise through a vascular route (MCC, n=6). Lymphatic capillary density (mm⁻²), as determined by immunohistochemical staining with the lymphatic specific marker LYVE-1, was significantly increased around MM (10.0±2.5 mm⁻²) compared with normal dermis (2.4±0.9 mm⁻²), BCC (3.0±0.9 mm⁻²) and MCC (2.4±1.4 mm⁻²) (P<0.0001). There was a small decrease in LD inside MM (1.1±0.7 mm⁻²) compared with normal dermis, but a highly significant decrease in BCC (0.14±0.13) and MCC (0.12±2.4) (P<0.01 Kruskal–Wallis). Astonishingly, LD discriminated between melanomas that subsequently metastasised (12.8±1.6 mm⁻²) and those that did not (5.4±1.1 mm⁻², P<0.01, Mann–Whitney). Lymphatic invasion by tumour cells was seen mainly in MM that metastasised (70% compared with 12% not metastasising, P<0.05 Fisher's Exact test). The results show that LD was increased around MMs, and that LD and tumour cell invasion of lymphatics may help to predict metastasis. To this end, a prognostic index was calculated using LD, lymphatic invasion and thickness that clearly discriminated metastatic from nonmetastatic tumours.

Selective immunohistochemical staining shows significant prognostic influence of lymphatic and blood vessels in patients with malignant melanoma

Few data on the influence of lymphatic microvessel density (LMVD) on survival in patients with melanoma are available. The aim of this study was to assess LMVD and blood microvessel density (MVD) in tissue samples from 120 patients with melanoma. LMVD was stained with an antibody staining for podoplanin, and blood MVD was assessed by CD31 (PECAM-1)-immunostaining. Survival was determined using univariate and multivariate analysis. A significant association between a high CD31 MVD (but not LMVD) and the presence of lymph node metastases (P=0.007) was observed. Patients with a high LMVD had a significant shorter overall (OS) (P=0.0436) and disease-free survival (DFS) (P=0.0249) in univariate analysis. The survival analysis showed CD31 MVD was a strong prognostic factor for OS and DFS in both uni-and multivariate analyses. Our results demonstrate LMVD as a prognostic factor in malignant melanoma, although its prognostic relevance is much smaller compared with blood MVD.

Micro-MRI at 11.7 T of a Murine Brain Tumor Model Using Delayed Contrast Enhancement

In vivo imaging methodologies allow for serial measurement of tumor size, circumventing the need for sacrificing mice at given time points. In orthotopically transplanted murine models of brain tumors, cross-section micro-MRI allows for visualization and measurement of the physically inaccessible tumors. To allow for long resident times of a contrast agent in the tumor, intraperitoneal administration was used as a route of injection for contrast-enhanced micro-MRI, and a simple method for relative tumor volume measurements was examined. A strategy for visualizing the variability of the delayed tumor enhancement was developed. These strategies were applied to monitor the growth of brain tumors xenotransplanted into nude mice and either treated with the antiangiogenic peptide EMD 121974 or an inactive control peptide. Each mouse was used as its own control. Serial imaging was done weekly, beginning at Day 7 after tumor cell implantation and continued for 7 weeks. Images obtained were reconstructed on the MRI instrument. The image files were transferred off line to be postprocessed to assess tumor growth (volume) and variability in enhancement (three-dimensional [3-D] intensity models). In a small study, tumor growth and response to treatment were followed using this methodology and the high-resolution images displayed in 3-D allowed for straightforward qualitative assessment of variable enhancement related to vascular factors and tumor age.

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.

Lymphatic vessel activation in cancer

Metastasis of most cancers occurs primarily through the lymphatic system, and the extent of lymph node involvement is the most important prognostic indicator. While the importance of the lymphatic system as a pathway for metastasis has been well recognized, there is very little information available about the mechanisms by which tumor cells interact with the lymphatics. Recently, production of the lymphangiogenic factor VEGF-C has been detected in tumors, and the significance of VEGF-C-mediated lymphangiogenesis for tumor metastasis has been demonstrated. Increased lymphatic vessel density has been found associated with certain tumors. The mechanisms by which tumor cells gain access to and enter lymphatic vessels are critical issues that need to be addressed in the future. In contrast to the prevailing view that has assigned to the lymphatic system a passive role in the metastatic process, our results indicate the importance of lymphatic vessel activation in tumor dissemination.