Increased intratumoral lymphatic vessel density correlates with lymph node metastasis in early gastric carcinoma

Development and Validation of a Computed Tomography-Based Radiomics Nomogram for the Preoperative Prediction of Central Lymph Node Metastasis in Papillary Thyroid Microcarcinoma

RATIONALE AND OBJECTIVES

This study aims to develop and validate a computed tomography (CT)-based radiomics nomogram for pre-operatively predicting central lymph node metastasis (CLNM) in patients with papillary thyroid microcarcinoma (PTMC) and explore the underlying biological basis by using RNA sequencing data.

METHODS

This study trained 452 PTMC patients across two hospitals from January 2012 to December 2020. The sets were randomly divided into the training (n = 339), internal test (n = 86), external test (n = 27) sets. Radiomics features were extracted from primary lesion's pre-operative CT images for each patient. After screening for features, five algorithms such as K-nearest neighbor, logistics regression, linear-support vector machine (SVM), Gaussian SVM, and polynomial SVM were used to establish the radiomics models. The performance of these five algorithms was evaluated and compared directly to radiologist's interpretation (CT-reported lymph node status). The radiomics signature score (Rad-score) was generated using a linear combination of the selected features. By combining the clinical risk factors and Rad score, a radiomics nomogram was established and compared with Rad-score and clinical model. The performance of the nomogram was evaluated based on the receiver operating characteristic (ROC) curve, calibration curve, and the decision curve analysis (DCA). The potential biological basis of nomogram was revealed by performing genetic analysis based on the RNA sequencing data.

RESULTS

A total of 25 radiomic features were ultimately selected to train the machine learning models, and the five machine learning models outperformed the radiologists' interpretation by achieving area under the ROC curves (AUCs) ranging from 0.606 to 0.730 in the internal test set. By incorporating the Rad score and clinical risk factors (sex, age, tumor-diameter, and CT-reported lymph node status), this nomogram achieved AUCs of 0.800 and 0.803 in the internal and external test set, which were higher than that of the Rad-score and clinical model, respectively. Calibration curves and DCA also showed that the nomogram had good performance. As for the biological basis exploration, in patients predicted by nomogram to be PTC patients with CLMN, 109 genes were dysregulated, and some of them were associated with pathways and biological processes such as tumor angiogenesis.

CONCLUSION

This radiomics nomogram successfully identified CLNM on pretreatment imaging across multiple institutions, exceeding the diagnostic ability of radiologists and had the potential to be integrated into clinical decision making as a non-invasive pre-operative tool.

Expression of CD44v6 and lymphatic vessel density in early gastric cancer tissues and their clinical significance

Objective:

To explore the relationships between expression of CD44v6, lymphatic vessel density (LVD) and the clinicopathological parameters of patients.

Methods:

One hundred early gastric cancer tissues, 55 high-grade gastric intraepithelial neoplasia (HGIN) tissues, 60 low-grade gastric intraepithelial neoplasia (LGIN) tissues and 60 chronic superficial gastritis tissues were collected and set as gastric cancer group, HGIN group, LGIN group and gastritis group respectively. The expression of CD44v6 and LVD of patients in all the groups were detected using two-step immunohistochemical method to analyze the relationships between the expression of CD44v6 and lymphatic vessel density in early gastric cancer tissues and their relationships with the clinicopathological parameters of patients. The values of LVD in predicting lymph node metastasis in early gastric cancer were evaluated using receiver operating characteristic (ROC) curve.

Results:

The positive expression of CD44v6 and LVD in the gastritis group, LGIN group, HGIN group and gastric cancer group gradually increased. The positive expression of CD44v6 and LVD in early gastric cancer tissues were in no correlation with the gender, age, tumor site, maximum diameter, differentiation degree and invasion depth (P>0.05) and in a correlation with lymphatic metastasis and lymphatic vessel invasion (P<0.06). The positive expression of CD44v6 in the early gastric cancer tissues was in a positive correlation with LVD (P<0.05). The analysis of ROC curves suggested that the area under ROC curve of predicting lymphatic metastasis of early gastric cancer with LVD was 0.837 (95% CI: 0.756~0.910), and the cut-off value was 14; the corresponding sensitivity and specificity were 63.6% and 90.2 respectively.

Conclusion:

The expression of CD44v6 and LVD in early gastric cancer tissues are in a close correlation with the clinicopathologic features, and joint detection of expression of CD44v6 and LVD can be taken as the indicator of gastric cancer metastasis.

Risk factors for lymph node metastasis in non-sentinel node basins in early gastric cancer: sentinel node concept

BACKGROUND

Sentinel node (SN) concept is being applied to early gastric cancer. However, when SNs are positive for metastasis, it is unclear how often LNs in other LN basins show metastasis. We aimed to investigate LN metastasis possibility in LN basins without SNs (non-SN basins). We determined risk factors for metastasis in non-SN basins and identified a prediction model for non-SN basin metastasis using classification and regression tree (CART) analysis.

METHODS

We enrolled 550 patients who were diagnosed with cT1N0M0 or cT2N0M0 gastric cancer with a single lesion and underwent SN mapping. We adopted a dual-tracer method using a radioactive colloid and blue dye to detect SNs.

RESULTS

Of all, 45 (8.2%) patients had SN metastasis; we divided them into two groups: LN metastasis positive and LN metastasis negative in non-SN basins. Univariate analysis showed that the groups differed significantly regarding lymphatic invasion (p = 0.007), number of identified SNs (p = 0.032), and macrometastasis in SN basins (p = 0.005). The CART decision tree for predicting LN metastasis in non-SN basins had area under the curve value of 0.86. Moreover, there were significantly differences in cancer-specific survival (CSS) between the two groups (p = 0.028).

CONCLUSIONS

Macrometastasis in SN basins, lymphatic invasion, and number of identified SNs ≥ 5 are risk factors for LN metastasis in non-SN basins among gastric cancer patients. We identified a prediction model with CART analysis; patients with macrometastasis in SN basins and lymphatic invasion were considered to be at the highest risk for LN metastasis.

Neoangiogenesis of gastric submucosa-invasive adenocarcinoma

Early gastric cancer may be defined as mucosal or submucosal invasive carcinoma, and exhibits a good prognosis: 90% of patients survive >10 years. Early gastric cancer infrequently exhibits lymph node metastasis, although submucosal invasion, the presence of vascular invasion and/or lymphatic permeation are independent risk factors for lymph node metastasis in early gastric cancer. The analysis of tumor lymphangiogenesis and angiogenesis are important to determine the extent of invasive progression and metastasis in patients. Previously, the presence of vessels expressing the D2-40 antibody and the factor-VIII protein has been identified immunohistochemically. The vessels that are immunoreactive for D2-40 and factor-VIII are morphologically similar to lymphatic vessels or small-size veins, also termed venules. In the present study, the association between tumor invasion and neoangiogenesis in early gastric cancer was examined. The D2-40/factor-VIII double-stained vessel (DSV) density was analyzed, in addition to lymphatic and blood vessel (vein and artery) density, using 46 submucosa-invasive and 50 mucosal carcinomas, and 20 non-neoplastic gastric tissues. The lymphatic density and DSV density of submucosa beneath the carcinoma and submucosa of the surrounding region in submucosa-invasive carcinoma were significantly increased (P<0.001) in comparison with those in mucosal carcinoma or non-neoplastic gastric tissue. No significant difference was observed in blood vessel density between non-neoplastic gastric, mucosal carcinoma and submucosa-invasive carcinoma tissues other than that of mucosa. The present study suggests the potential for the presence of D2-40/factor-VIII DSV and the importance of this vessel for neoangiogenesis in early gastric cancer.

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.

Clinicopathological significance and prognostic role of microvessel density in gastric cancer: A meta-analysis

OBJECTIVE

The aim of this study was to elucidate the clinicopathological significance and prognostic role of microvessel density (MVD) in gastric cancer (GC) through a meta-analysis.

METHODS

This meta-analysis included 4094 patients from 26 eligible studies. We investigated the correlation between MVD and clinicopathological characteristics, including survival rate. In addition, subgroup analysis based on microscopic magnification among evaluation criteria of MVD was performed.

RESULTS

High MVD was significantly correlated with worse overall and disease-free survival rates [hazard ratio (HR), 3.028, 95% confidence interval (CI) 2.105-4.357 and HR 2.045, 95% CI 1.530-2.732, respectively]. MVD was significantly increased in GC with diffuse type of Lauren's classification [mean difference (MD) 3.091, 95% CI 0.615-5.567], lymphatic invasion (MD 8.262, 95% CI 3.310-13.214), lymph node metastasis (MD 5.730, 95% CI 2.444-9.016), higher pT stage (pT3-4) (MD 7.093, 95% CI 0.060-14.126) and higher pTNM stage (III-IV) (MD 3.023, 95% CI 0.181-5.865). However, MD of MVD was not significantly different in regard to vascular invasion (MD 7.430, 95% CI 1.015-15.875), tumor differentiation (MD 5.501, 95% CI 1.353-12.355) and tumor size (MD 4.731, 95% CI 2.003-11.465).

CONCLUSION

Taken together, higher MVD was significantly correlated with worse prognosis. In addition, MVD was significantly higher in GC with aggressive tumor behavior than in GC without aggressive features.

Prognostic value of lymphovascular invasion in Bismuth-Corlette type IV hilar cholangiocarcinoma

AIM

To assess the prognostic value of lymphovascular invasion (LVI) in Bismuth-Corlette type IV hilar cholangiocarcinoma (HC) patients.

METHODS

A retrospective analysis was performed on 142 consecutively recruited type IV HC patients undergoing radical resection with at least 5 years of follow-up. Survival analysis was performed by the Kaplan-Meier method, and the association between the clinicopathologic variables and survival was evaluated by log-rank test. Multivariate analysis was adopted to identify the independent prognostic factors for overall survival (OS) and disease-free survival (DFS). Multiple logistic regression analysis was performed to determine the association between LVI and potential variables.

RESULTS

LVI was confirmed histopathologically in 29 (20.4%) patients. Multivariate analysis showed that positive resection margin (HR = 6.255, 95%CI: 3.485-11.229, P < 0.001), N1 stage (HR = 2.902, 95%CI: 1.132-7.439, P = 0.027), tumor size > 30 mm (HR = 1.942, 95%CI: 1.176-3.209, P = 0.010) and LVI positivity (HR = 2.799, 95%CI: 1.588-4.935, P < 0.001) were adverse prognostic factors for DFS. The independent risk factors for OS were positive resection margin (HR = 6.776, 95%CI: 3.988-11.479, P < 0.001), N1 stage (HR = 2.827, 95%CI: 1.243-6.429, P = 0.013), tumor size > 30 mm (HR = 1.739, 95%CI: 1.101-2.745, P = 0.018) and LVI positivity (HR = 2.908, 95%CI: 1.712-4.938, P < 0.001). LVI was associated with N1 stage and tumor size > 30 mm. Multiple logistic regression analysis indicated that N1 stage (HR = 3.312, 95%CI: 1.338-8.198, P = 0.026) and tumor size > 30 mm (HR = 3.258, 95%CI: 1.288-8.236, P = 0.013) were associated with LVI.

CONCLUSION

LVI is associated with N1 stage and tumor size > 30 mm and adversely influences DFS and OS in type IV HC patients.

Contrast-enhanced ultrasonography features of papillary thyroid carcinoma for predicting cervical lymph node metastasis

The present study was performed to evaluate the predictive value of contrast-enhanced ultrasonography (CEUS) for the risk of cervical lymph node metastasis (LNM) in papillary thyroid carcinoma (PTC). Between May 2014 and November 2016, 42 patients who received surgery for suspicious PTCs were enrolled in the present study. Each individual underwent CEUS with conventional ultrasound (US), preoperative US-guided fine needle aspiration and personalized surgery. Subsequently, the microvascular density (MVD) of all surgical specimens was measured. According to the results of surgical histopathology, individuals were divided into two groups: LNM⁺ (PTCs with LNM), and LNM⁻ (PTCs without LNM). Clinicopathological characteristics, CEUS enhancement patterns, perfusion parameters and measurements of MVD were compared. The correlation between quantitative variables and LNM was analyzed using Spearman's correlation analysis. Compared with that in the LNM⁻ group, patients in the LNM⁺ group were younger (P<0.05) and had a larger mean tumor size (P<0.05). The incidence ratio of patients who were ≤45 years old (P<0.05), tumors >10 mm in size (P<0.05) and capsular infiltration (P<0.05) were statistically higher in the LNM⁺ group. Following the use of a novel classification system, the ratio of PTCs with early partial hyper-enhancement was identified to be significantly higher in the LNM⁺ group (P<0.01). The mean intensity, intensity increase velocity, MVD ratio and mean intensity ratio of intratumoral/peripheral thyroid parenchyma (MIR) were statistically higher in the LNM⁺ group compared with that in the LNM⁻ group (all P<0.05). MIR was identified to be positive correlated with LNM (P<0.05). A MIR value of 0.86 was the optimal threshold of LNM in PTCs. In conclusion, LNM may rely on the local rich blood supply of PTC lesions. Partial hyper-enhancements of CEUS and higher values of MIR may suggest a high risk for LNM in PTC.

Prediction of lymph node metastasis and sentinel node navigation surgery for patients with early-stage gastric cancer

Accurate prediction of lymph node (LN) status is crucially important for appropriate treatment planning in patients with early gastric cancer (EGC). However, consensus on patient and tumor characteristics associated with LN metastasis are yet to be reached. Through systematic search, we identified several independent variables associated with LN metastasis in EGC, which should be included in future research to assess which of these variables remain as significant predictors of LN metastasis. On the other hand, even if we use these promising parameters, we should realize the limitation and the difficulty of predicting LN metastasis accurately. The sentinel LN (SLN) is defined as first possible site to receive cancer cells along the route of lymphatic drainage from the primary tumor. The absence of metastasis in SLN is believed to correlate with the absence of metastasis in downstream LNs. In this review, we have attempted to focus on several independent parameters which have close relationship between tumor and LN metastasis in EGC. In addition, we evaluated the history of sentinel node navigation surgery and the usefulness for EGC.

[Markers of angiogenesis in tumor growth]

Angiogenesis is a process of new blood vessels formation. The role of angiogenesis in growth, invasion and metastasis of malignant tumours is nowdays universally recognized. Though, investigation of mechanisms of blood vessels formation and elaboration methods for assessment of tumour angiogenesis are still up-dated. Another important concern are different aspects of usage of immunohistochemical markers of blood vessels endothelium (CD31 and CD34) for assessment of tumour aggressiveness and prognosis. The problems of malignant lymphangiogenesis are also up-to-date. The focus is on methods of immunohistochemical visualization of forming lymphatic vessels, role of podoplanin, the most reliable marker of lymphatic vessels, in their identification, and formulization of the main criteria for lymphangiogenesis estimation, its correlation with metastatic activity and prognostic potential. Studying of angiogenesis and lymph angiogenesis in malignant tumors is important and challenging direction for researching tumour progression and invention of antiangiogenic therapy.

Tumor lymphangiogenesis and new drug development

Traditionally, tumor-associated lymphatic vessels have been regarded as passive by-standers, serving simply as a drainage system for interstitial fluid generated within the tumor. However, with growing evidence that tumors actively induce lymphangiogenesis, and that the number of lymphatic vessels closely correlates with metastasis and clinical outcome in various types of cancer, this picture has changed dramatically in recent years. Tumor-associated lymphatic vessels have now emerged as a valid therapeutic target to control metastatic disease, and the first specific anti-lymphangiogenic drugs have recently entered clinical testing. Furthermore, we are just beginning to understand the whole functional spectrum of tumor-associated lymphatic vessels, which not only concerns transport of fluid and metastatic cells, but also includes the regulation of cancer stemness and specific inhibition of immune responses, opening new venues for therapeutic applications. Therefore, we predict that specific targeting of lymphatic vessels and their function will become an important tool for future cancer treatment.

Tight junction protein claudin 4 in gastric carcinoma and its relation to lymphangiogenic activity

BACKGROUND AND STUDY AIMS

Gastric cancer is the second most common cause of cancer-related death worldwide. Claudins are a family of tight junction proteins that are biologically relevant in many cancer progression steps. This study aimed to investigate the expression of the intestinal claudin (claudin 4) in gastric carcinoma and to evaluate its relation to the different clinicopathologic prognostic parameters, especially lymphangiogenesis (production of new lymphatic vessels, measured by lymphovascular density (LVD)) and lymphovascular invasion (LVI).

PATIENTS AND METHODS

Fifty-five gastric carcinoma specimens were immunohistochemically stained for claudin 4 and D2-40 (for detection of lymphatic vessel endothelium).

RESULTS

High expression of claudin 4 was detected in 26 of 55 (47.3%) cases. Low expression of claudin 4 was related to poorly differentiated type (p=0.001), non-intestinal (diffuse) type (p=0.001), deeper tumour invasion (p<0.001), lymph node metastasis (p=0.001), and higher stage (p=0.001). In addition, higher LVD was related to poorly differentiated types (p=0.001), non-intestinal type (p=0.001), lymph node metastasis (p=0.015), and higher tumour, node, metastasis (TNM) stage (p=0.001). LVI was related to lymph node metastasis (p=0.025), higher TNM stage (p=0.001), and LVD (p=0.001). Claudin 4 significantly correlated with both LVD (p=0.009) and LVI (p=0.009).

CONCLUSIONS

High expression of claudin 4 was associated with the more differentiated intestinal-type gastric carcinoma and lost in poorly differentiated diffuse type. So, claudin 4 may be used as one of the differentiating markers between the two major types of gastric carcinoma (intestinal vs. diffuse). LVD and LVI were related to higher incidence of lymph node metastasis and therefore could be used as predictive markers for lymph node metastasis in limited specimens during early gastric carcinoma to determine the need for more invasive surgery. Low expression of claudin 4 was related to lymphangiogenesis. This may shed light on the relation of tight junction protein expression and lymphangiogenesis.

The different role of intratumoral and peritumoral lymphangiogenesis in gastric cancer progression and prognosis

Background

Tumor-induced lymphangiogenesis plays a crucial role in metastasis and tumor progression. However, the significance of intratumoral lymphovascular density (I-LVD) and peritumoral lymphovascular density (P-LVD) has been controversial in gastric cancer. The purpose of this study was to investigate the differences of clinicopathologic characteristics with respect to I-LVD and P-LVD in gastric cancer.

Methods

Samples of I-LVD and P-LVD from 66 patients who had undergone radical gastrectomy for gastric cancer were assessed after staining with D2-40, an immunostaining marker for lymphatic endothelium. The mean number of lymphatic vessels in three hotspots was calculated in intratumoral and peritumoral areas.

Results

The peritumoral lymphatics were enlarged with dilated lumens compared to the intratumoral lymphatics. I-LVD was positively correlated with diffuse gastric cancer subtype, tumor stage, lymphovascular invasion, tumor node metastasis stage, and overall survival (P <0.05). P-LVD was associated with lymphovascular invasion, node stage, and disease-free survival (P <0.05).

Conclusions

We conclude that P-LVD had an important role in lymph node metastasis, while I-LVD was more associated with depth of tumor invasion. However, both LVDs contributed to gastric cancer progression and prognosis.

Lymphangiogenesis in early and advanced gastric cancer: is there any difference?

BACKGROUND AND AIM

Gastric cancer (GC) in Poland is on the third place of men's mortality and on the fifth place of women's mortality in malignant neoplasms, and the percentage of diagnosed early GC is less than 20%. In this study, the relationship among lymphatic vessel density, marked with D2-40, expression of vascular endothelial growth factor (VEGF)-C/D, VEGF receptor 3 VEGFR-3, and the stage of GC patient were investigated.

METHODS

This study examined the relationships between the peritumoral lymphatic vessels (PTL) density and intratumoral lymphatic vessels (ITL) density stained immunohistochemically with D2-40/podoplanin, the expression of VEGF-C/D and VEGFR-3, and the stage of 58 GC patients.

RESULTS

Lymphatic vessel density measured by D2-40 decreases outside the tumor (PTL) and increases within the tumor (ITL) as the staging grows from I to III, whereas in the case of patients belonging to stage IV group, lymphatic vessel density decreases outside the tumor as well as within the tumor in comparison with the stage III group (not statistically significant). We observed a difference between morphology of the vessels within the tumor (ITLs) and vessels that are located outside the tumor (PTLs). PTLs were enlarged and unsqueezed as opposed to ITLs, which were collapsed.

CONCLUSIONS

(i) There is no significant correlation between the density of ITL nor PTL marked with D2-40 and the stage of GC. (ii) We did not observe relationship between expression of VEGF-C/D and VEGFR-3 and the stage of GC. (iii) Further studies are needed to fully determine the role of PTL and ITL.

Can increased tumoral vascularity be a quantitative predicting factor of lymph node metastasis in papillary thyroid microcarcinoma?

The aim of the present study was to evaluate the clinical implications of the vascular index (VI) as a predicting factor for central and lateral lymph node metastasis (LNM) in patients with papillary thyroid microcarcinoma (PTMC). From January 2011 to October 2011, 588 patients (495 females, 93 males) who were diagnosed with PTMC were included. Clinicopathologic characteristics of patients and ultrasound (US) features of the lesions including VI were evaluated retrospectively. The VI was measured with QLAB 7.0 quantification software using preoperative Doppler US images. Univariate and multivariate analysis were used to assess predictive factors of LNM. From 588 patients, 140 patients (23.8 %) had central LNM and 26 patients (4.4 %) had lateral LNM on pathologic results. The presence of lateral LNM [odds ratio (OR) 5.46; 95 % confidence interval (CI) = 2.19-13.64], bilaterality (OR 2.16; 95 % CI 1.17-4.01), and increased tumor size (OR 1.15; 95 % CI 1.04-1.28) were significant independent factors for predicting central LNM. The presence of central LNM (OR 5.58; 95 % CI 2.22-14.04), upper third location of malignancy (OR 2.50; 95 % CI 1.01-6.21), and tumor size (OR 1.34; 95 % CI 1.03-1.73) were significant independent factors for predicting lateral LNM. However, the VI was not a significant predicting factor for both central and lateral LNM. Therefore, the VI of PTMC may not be useful for predicting central and lateral LNM in patients with PTMC.

Unveiling lymph node metastasis in early gastric cancer

With respect to gastric cancer treatment, improvements in endoscopic techniques and novel therapeutic modalities [such as endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD)] have been developed. Currently, EMR/ESD procedures are widely accepted treatment modalities for early gastric cancer (EGC). These procedures are most widely accepted in Asia, including in Korea and Japan. In the present era of endoscopic resection, accurate prediction of lymph node (LN) metastasis is a critical component of selecting suitable patients for EMR/ESD. Generally, indications for EMR/ESD are based on large Japanese datasets, which indicate that there is almost no risk of LN metastasis in the subgroup of EGC cases. However, there is some controversy among investigators regarding the validity of these criteria. Further, there are currently no accurate methods to predict LN metastasis in gastric cancer (for example, radiologic methods or methods based on molecular biomarkers). We recommend the use of a 2-step method for the management of early gastric cancer using endoscopic resection. The first step is the selection of suitable patients for endoscopic resection, based on endoscopic and histopathologic findings. After endoscopic resection, additional surgical intervention could be determined on the basis of a comprehensive review of the endoscopic mucosal resection/endoscopic submucosal dissection specimen, including lymphovascular tumor emboli, tumor size, histologic type, and depth of invasion. However, evaluation of clinical application data is essential for validating this recommendation. Moreover, gastroenterologists, surgeons, and pathologists should closely collaborate and communicate during these decision-making processes.

Molecular mechanism underlying lymphatic metastasis in pancreatic cancer

As the most challenging human malignancies, pancreatic cancer is characterized by its insidious symptoms, low rate of surgical resection, high risk of local invasion, metastasis and recurrence, and overall dismal prognosis. Lymphatic metastasis, above all, is recognized as an early adverse event in progression of pancreatic cancer and has been described to be an independent poor prognostic factor. It should be noted that the occurrence of lymphatic metastasis is not a casual or stochastic but an ineluctable and designed event. Increasing evidences suggest that metastasis-initiating cells (MICs) and the microenvironments may act as a double-reed style in this crime. However, the exact mechanisms on how they function synergistically for this dismal clinical course remain largely elusive. Therefore, a better understanding of its molecular and cellular mechanisms involved in pancreatic lymphatic metastasis is urgently required. In this review, we will summarize the latest advances on lymphatic metastasis in pancreatic cancer.

Inducible nitric oxide synthase expression in gastric adenocarcinoma: impact on lymphangiogenesis and lymphatic metastasis

Background

Lymphatic metastasis is the most important parameter in the spread of gastric carcinomas. Nitric oxide (NO) is a signaling molecule that plays an important role in inflammation and carcinogenesis. In this study, the possible link between inducible nitric oxide synthase (iNOS) expression with lymphangiogenesis and the clinicopathological parameters of gastric carcinomas was investigated.

Methods

In this study, iNOS expression and D2-40 (lymphatic endothelium-specific marker monoclonal antibody) reactivity were examined immunohistochemically in 41 gastric adenocarcinoma and 20 non-neoplastic gastric tissues. iNOS expression was scored semiquantitatively in the tumor parenchyma and stroma. D2-40-positive lymphatic vessels were used in the determination of lymphatic invasion and intratumoral and peritumoral lymphatic vascular density.

Results

iNOS expression was higher in gastric carcinoma tissue compared with non-neoplastic tissue. Particularly, iNOS expression in tumor cells was found to be closely related to lymphangiogenesis and lymphatic metastasis. The density of lymphatic invasion as well as intratumoral and peritumoral lymphatic vascular density were positively correlated with lymph node metastasis.

Conclusions

Our results suggest that iNOS-mediated NO formation plays an important role in gastric carcinogenesis, tumor lymphangiogenesis, and the development of lymphatic metastases. Inhibition of the NO pathway may be an alternative treatment of gastric carcinomas.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1713572940104388.

Inhibition of c-Met reduces lymphatic metastasis in RIP-Tag2 transgenic mice

Inhibition of VEGF signaling can promote lymph node metastasis in preclinical models, but the mechanism is not fully understood, and successful methods of prevention have not been found. Signaling of hepatocyte growth factor (HGF) and its receptor c-Met can promote the growth of lymphatics and metastasis of some tumors. We sought to explore the contributions of c-Met signaling to lymph node metastasis after inhibition of VEGF signaling. In particular, we examined whether c-Met is upregulated in lymphatics in or near pancreatic neuroendocrine tumors in RIP-Tag2 transgenic mice and whether lymph node metastasis can be reduced by concurrent inhibition of VEGF and c-Met signaling. Inhibition of VEGF signaling by anti-VEGF antibody or sunitinib in mice from the age of 14 to 17 weeks was accompanied by more intratumoral lymphatics, more tumor cells inside lymphatics, and more lymph node metastases. Under these conditions, lymphatic endothelial cells, like tumor cells, had strong immunoreactivity for c-Met and phospho-c-Met. c-Met blockade by the selective inhibitor, PF-04217903, significantly reduced metastasis to local lymph nodes. Together, these results indicate that inhibition of VEGF signaling in RIP-Tag2 mice upregulates c-Met expression in lymphatic endothelial cells, increases the number of intratumoral lymphatics and number of tumor cells within lymphatics, and promotes metastasis to local lymph nodes. Prevention of lymph node metastasis by PF-04217903 in this setting implicates c-Met signaling in tumor cell spread to lymph nodes.

The risk factors for lymph node metastasis in early gastric cancer patients who underwent endoscopic resection: is the minimal lymph node dissection applicable? A retrospective study

PURPOSE

The purpose of this study was to identify risk factors associated with lymph node (LN) metastasis in early gastric cancer patients who underwent endoscopic resection (ER) and to evaluate the feasibility of minimal LN dissection in these patients.

METHODS

From January 2001 to March 2011, patients who underwent gastrectomy with lymphadenectomy due to the potential risk of LN metastasis after ER were enrolled at National Cancer Center, Korea. The incidence, risk factors, and distribution of LN metastasis were evaluated.

RESULTS

Of the 147 enrolled patients, the LN metastasis was identified in 12 patients (8.2%). The incidence of LN metastasis was not significantly increased in patients with submucosal invasion, lymphovascular invasion, and mixed undifferentiated histology [odds ratio (OR), 5.55, 1.349, and 0.387; 95% confidence interval (CI), 0.688-43.943, 0.405-4.494, and 0.081-1.84, respectively]. Tumor size more than 2 cm was significantly associated with LN metastasis (OR, 14.056; 95% CI, 1.76-112.267). The incidence of LN metastasis gradually increased from 3.2 to 20%, as number of risk factors increased (P = 0.019). LN metastasis was present primarily along the perigastric area in all except two patients (1.4%) with skip metastasis to extragastric area.

CONCLUSIONS

Standard surgery with at least D1 + LN dissection must be recommended for patients who proved to have risk factors for LN metastasis after ER, because the potential of skip metastasis is not negligible. Nevertheless, the minimal LN dissection, such as sentinel basin dissection, might be applied cautiously in patients with small-sized tumors after ER.

Peritumoral lymphangiogenesis induced by vascular endothelial growth factor C and D promotes lymph node metastasis in breast cancer patients

BACKGROUND

Mounting clinical and experimental data suggest that the migration of tumor cells into lymph nodes is greatly facilitated by lymphangiogenesis. Vascular endothelial growth factor (VEGF)-C and D have been identified as lymphangiogenic growth factors and play an important role in tumor lymphangiogenesis. The purpose of this study was to investigate the location of lymphangiogenesis driven by tumor-derived VEGF-C/D in breast cancer, and to determine the role of intratumoral and peritumoral lymphatic vessel density (LVD) in lymphangiogenesis in breast cancer.

METHODS

The expression levels of VEGF-C/D were determined by immunohistochemistry, and intratumoral LVD and peritumoral LVD were assessed using immunohistochemistry and the D2-40 antibody in 73 patients with primary breast cancer. The associations of intratumoral LVD and peritumoral LVD with VEGF-C/D expression, clinicopathological features and prognosis were assessed.

RESULTS

VEGF-C and D expression were significantly higher in breast cancer than benign disease (P < 0.01). VEGF-C (P < 0.001) and VEGF-D (P = 0.005) expression were significantly associated with peritumoral LVD, but not intratumoral LVD. Intratumoral LVD was associated with tumor size (P = 0.01). Peritumoral LVD was significantly associated with lymph node metastasis (LNM; P = 0.005), lymphatic vessel invasion (LVI; P = 0.017) and late tumor,node, metastasis (TNM) stage (P = 0.011). Moreover, peritumoral LVD was an independent risk factor for axillary lymph node metastasis, overall survival and disease-free survival in multivariate analysis.

CONCLUSIONS

This study suggests that tumor-derived VEGF-C/D induce peritumoral lymphangiogenesis, which may be one mechanism that leads to lymphatic invasion and metastatic spread. Peritumoral LVD has potential as an independent prognostic factor in breast cancer patients.

Molecular regulation of lymphangiogenesis in development and tumor microenvironment

A rapid progress has been made in the field of lymphatic research during the last 15 years. This includes better understanding of the cellular events and molecular players involved in the lymphatic vessel formation and remodeling in development. The key players identified in developmental lymphangiogenesis, including vascular endothelial cell growth factor-C (VEGF-C) / VEGFR-3 and angiopoietins (ANGPTs)/ TIE pathways, are also crucial for pathological lymphatic vessel growth. In solid tumor, tumor cells as well as tumor-associated stromal cells, such as tumor-infiltrating leukocytes, contribute to intra- and peri-tumoral lymphangiogenesis via secreting lymphangiogenic growth factors. Tumor-associated lymphatic endothelial cells also interact actively with tumor cells and leukocytes via secreting various chemokines. It has been well established that tumor lymphangiogenesis promotes tumor cell dissemination to regional lymph nodes. Thus manipulation of lymphangiogenic microenvironment could become another valuable approach in the combat of tumor progression.

Analysis of pancreatic cancer microenvironment: role of macrophage infiltrates and growth factors expression

Background: Research over the last twenty years has yielded much insight into pancreatic cancer biology, but it has neither improved diagnostics methods nor the way of treatment. The question remains as to what the critical deciding factor is in making pancreatic cancer such an aggressive disease.

Methods: Pancreatic tumor tissue came from 36 patients. To assess lymphatic vessels color lymphangiography and immunohistochemistry were used. Activity of matrix metalloproteinases was studied with gel and in situ zymography. Expression of growth factors and infiltrating immune cells were investigated using immunohistochemistry.

Results: Our study revealed that the structures that correspond to lymphatic vessels were not observed in tumor center but only at the edge of the tumor. All studied growth factors were present in tumor tissue. We found that the difference in expression between G2 and G3 stage was statistically relevant in cases of c-Met receptor. Inflammatory cells were present around neoplastic glands and also strongly around nerves infiltrated by cancer cells. The number of infiltrating macrophages in tumor tissue was significantly higher in group with metastases to lymph nodes.

Conclusion: We showed two factors that influence pancreatic cancer progression and invasion: c-Met receptors and macrophages infiltrating tumor tissue. Based on our analysis, this indicates that epithelial-mesenchymal transition might be crucial in the progression of pancreatic cancer.

Microvessel Density Is Associated with VEGF and α-SMA Expression in Different Regions of Human Gastrointestinal Carcinomas

Tumor angiogenesis is known to be regulated by growth factors secreted by host and tumor cells. Despite the importance of tumor vasculature and angiogenic heterogeneity in solid tumors, few studies have compared the vasculature in different regions of human cancer. Blood vessels from different regions of carcinomas might have morphofunctional implications in tumor angiogenesis. In the present study, therefore, we have examined the relationship between microvascular density (MVD) and vascular endothelial growth factor (VEGF) expression and alpha smooth muscle actin (α-SMA) expression in the center of the tumor (CT), periphery (P) and metastasis (M) regions from gastrointestinal carcinomas (GITC), as well as the association of MVD with clinicopathological factors. Surgically resected specimens corresponding to the CT, P and M from 27 patients were examined for FVIII, VEGF and α-SMA by immunohistochemistry. The MVD was not significantly different in the CT, P and M regions from GITC. The MVD in the VEGF positive group was significantly higher than in the VEGF negative group (CT, p = 0.034; P, p = 0.030; M, p = 0.032). The MVD as a function of α-SMA expression was also significantly higher in the CT and P region compared to the M region (p = 0.0008). In conclusion, the MVD association with VEGF and α-SMA expression, might indicate an increase of the number of neoformed and preexisting blood vessels uniformly or partially covered by pericytes in different regions of GITC, suggesting that not only MVD and VEGF are important parameters to the tumor vasculature, but also blood vessels maturation is a crucial factor for gastrointestinal tumor angiogenesis regulation and possible target of vascular therapy.

Different significance between intratumoral and peritumoral lymphatic vessel density in gastric cancer: a retrospective study of 123 cases

Background

Patients with gastric cancer in China have worse outcome and poorer prognosis. Tumor-induced lymphangiogenesis plays a crucial role in metastasis and tumor progression. The intratumoral and peritumoral lymphatics were supposed to have different biological effects. Three major growth factors, vascular endothelial growth factor- (VEGF)-A, VEGF-C and VEGF-D, are involved in the activation process via their receptors (VEGFRs). The purpose of current study is to investigate the significant difference between intratumoral and peritumoral lymphatic vessel density (LVD) in gastric cancer and their correlations with lymphangiogenetic growth factors.

Methods

Intratumoral LVD (I-LVD) and peritumoral LVD (P-LVD) of 123 patients with primary gastric cancer were assessed after staining with D2-40, and confirmed by double staining with D2-40/CD34. Proliferative activity of lymphatics endothelium was evaluated by double staining with D2-40/Ki-67. The associations were analyzed between I-LVD/P-LVD and the expression level of VEGF-A, VEGF-C, VEGF-D and the receptor VEGFR-3, which was measured by immunohistochemistry (IHC). The correlations of I-LVD and P-LVD with patient prognosis were also valued.

Results

(1) The peritumoral lymphatics (PTLs) were relatively enlarged with dilated lumen compared with the intratumoral lymphatics (ITLs). Increased P-LVD was significantly higher than I-LVD (P < 0.05). (2) P-LVD was found significantly associated with lymph node metastasis (LNM) (P < 0.001), lymphatic vessel invasion (LVI) (P < 0.001), VEGF-C (P = 0.003), VEGF-D expression level (P = 0.005) and VEGFR-3 expression level (P < 0.001) in peritumoral tissues, despite no significant association was found between above variants with I-LVD. However, increased I-LVD was demonstrated to be associated with decreased tumor volume (P < 0.001). Neither I-LVD nor P-LVD was correlated with VEGF-A expression (P > 0.05). (3) Proliferative activity of lymphatics endothelium was observed in PTLs, in spite of ITLs. (4) Increased P-LVD, but not I-LVD, was indicated to be an independent risk factor for lymph node metastasis by multivariate logistic regression analysis, and was related to worse disease-free survival and overall survival.

Conclusions

PTLs play roles in gastric cancer progression. Increased P-LVD, but not I-LVD, was significantly associated with VEGF-C/-D/VEGFR-3 system, and could be an independent risk factor for lymph node metastasis and a prognostic factor in gastric cancer.