Role of lymphangiogenesis in epithelial ovarian cancer

Lymphatic vasculature in ovarian cancer

Ovarian cancer (OVCA) is the second most common gynecological cancer and one of the leading causes of cancer related mortality among women. Recent studies suggest that among ovarian cancer patients at least 70% of the cases experience the involvement of lymph nodes and metastases through lymphatic vascular network. However, the impact of lymphatic system in the growth, spread and the evolution of ovarian cancer, its contribution towards the landscape of ovarian tissue resident immune cells and their metabolic responses is still a major knowledge gap. In this review first we present the epidemiological aspect of the OVCA, the lymphatic architecture of the ovary, we discuss the role of lymphatic circulation in regulation of ovarian tumor microenvironment, metabolic basis of the upregulation of lymphangiogenesis which is often observed during progression of ovarian metastasis and ascites development. Further we describe the implication of several mediators which influence both lymphatic vasculature as well as ovarian tumor microenvironment and conclude with several therapeutic strategies for targeting lymphatic vasculature in ovarian cancer progression in present day.

The prognostic influence of lymphatic endothelium-specific hyaluronan receptor 1 in cancer: A systematic review

Lymphangiogenesis is a key process in cancer development and metastasis. Lymphatic vessel endothelial hyaluronan receptor 1 (LYVE‐1) is a widely used marker for lymphatic endothelial cells (LEC), which also mediates immune and cancer cell migration. Recently, LYVE‐1–positive tumor cells were shown to acquire LEC‐like phenotype and exploit this receptor for lymphatic dissemination. Furthermore, selective targeting of LYVE‐1 impaired the growth of cancer‐related vasculature and reduced metastasis in vivo, signifying its role in therapeutic and prognostic applications. Although numerous studies have investigated the role of LYVE‐1 in cancer, a unifying detailed review of its prognostic utility is lacking to date. Thus, we compiled and critically appraised evidence from clinical studies comprising a total of 2352 patients diagnosed with different types of cancer and using a variety of experimental approaches. Collectively, most studies revealed a significant association between LYVE‐1 overexpression and dismal outcome of at least one survival estimate. Furthermore, the importance of vasculature location, intra‐ or peritumoral, and the influence of various lymphangiogenesis‐related parameters, such as lymphatic vessel density and invasion, were discussed. However, the specificity of LYVE‐1 staining is challenged by its expression in non‐LEC cells, implying the need for double labelling to better estimate its prognostic significance. In conclusion, this is to our knowledge the first comprehensive systematic review on the prognostic value of LYVE‐1 in cancer. More well‐designed studies across different populations and the development of standardized protocols would be paramount for the consistency of LYVE‐1 findings and for its potential transferability to clinical practice in future.

Baicalein: A metabolite with promising antineoplastic activity

Cancer, being a multifactorial disease has diverse presentation in different subgroups which is mainly attributed to heterogenous presentation of tumor cells. This cancer cell heterogeneity is the major reason for variable response to standard chemotherapeutic regimes owing to which high relapse rate and multi-drug resistance has increasingly been reported over the past decade. Interestingly, the research on natural compounds in combination with standard therapies have reported with interesting and promising results from the pre-clinical trials and few of which have also been tested in other phases of clinical trials. This review focusses on baicalein, an emerging anti-cancerous natural compound, its chemistry and mechanism of action. In view of promising pre-clinical this review is mainly motivated by the results observed from baicalein treatment of different cancer cell population. With the advancing scientific evidence on the anti-malignant potential of baicalein with respect to its pharmacological activities encompassing from anti-inflammatory to anti-angiogenic/anti-metastatic effects, the focus is mainly directed to understanding the precise mechanism of action of baicalein. In the process of understanding the underlying signaling cascades, the role of mitogen activated protein kinase (MAPK), mammalian target of rapamycin (mTOR), AKT serine/threonine protein kinase B (AKT), poly(ADP-ribose) polymerase (PARP), matrix metalloproteinases-2 (MMP-2), matrix metalloproteinases-9 (MMP-9) and caspase-3/-8,-9 have been highlighted as the major players for baicalein anti-malignant potential. This is also supported by the interesting pre-clinical findings which cumulatively pave the way ahead for development of baicalein as an adjunct anti-cancer treatment with chemotherapeutic agents.

Semaphorin 7A Promotes Macrophage-Mediated Lymphatic Remodeling during Postpartum Mammary Gland Involution and in Breast Cancer

Postpartum mammary gland involution is a tissue remodeling event that occurs in all mammals in the absence of nursing or after weaning to return the gland to the pre-pregnant state. The tissue microenvironment created by involution has proven to be tumor promotional. Here we report that the GPI-linked protein semaphorin 7A (SEMA7A) is expressed on mammary epithelial cells during involution and use preclinical models to demonstrate that tumors induced during involution express high levels of SEMA7A. Overexpression of SEMA7A promoted the presence of myeloid-derived podoplanin (PDPN)-expressing cells in the tumor microenvironment and during involution. SEMA7A drove the expression of PDPN in macrophages, which led to integrin- and PDPN-dependent motility and adherence to lymphatic endothelial cells to promote lymphangiogenesis. In support of this mechanism, mammary tissue from SEMA7A-knockout mice exhibited decreased myeloid-derived PDPN-expressing cells, PDPN-expressing endothelial cells, and lymphatic vessel density. Furthermore, coexpression of SEMA7A, PDPN, and macrophage marker CD68 predicted for decreased distant metastasis-free survival in a cohort of over 600 cases of breast cancer as well as in ovarian, lung, and gastric cancers. Together, our results indicate that SEMA7A may orchestrate macrophage-mediated lymphatic vessel remodeling, which in turn drives metastasis in breast cancer.Signficance: SEMA7A, which is expressed on mammary cells during glandular involution, alters macrophage biology and lymphangiogenesis to drive breast cancer metastasis. Cancer Res; 78(22); 6473-85. ©2018 AACR.

The prognostic significance of high/positive expression of tissue VEGF in ovarian cancer

Background & aim

At present, numerous reports have shown that high/positive expression of tissue vascular endothelial growth factor (VEGF) may be associated with the prognosis of patients with ovarian cancer. However, their results still remained controversy. Thus, this meta-analysis was designed to analyze and assess the prognostic value of tissue VEGF expression in patients with ovarian cancer.

Method

We searched PubMed, Embase, Cochrane Library and Web of Science to October, 2017. Hazard Ratio (HR) with its 95% confidence intervals (CIs) was used to evaluate the association between high/positive expression of tissue VEGF and the prognosis of ovarian cancer patients. All statistical analyses were performed using standard statistical procedures provided in RevMan 5.2.

Result

A total of 18 studies (including 1145 patients) were included for this meta-analysis. The positive/high expression of tissue VEGF had an obvious association with overall survival (OS) (HR 2.24, 95% CI 1.36–3.70; P=0.002), progression-free survival (PFS) (HR 1.60, 95% CI 1.11–2.31; P=0.01) and disease-free survival (DFS) (HR 3.49, 95% CI 1.27–9.56; P=0.02) of patients with ovarian cancer respectively.

Conclusion

The present meta-analysis indicated that positive/high expression of tissue VEGF may have a close association with survival of ovarian cancer.

Correlation between lymphatic endothelial markers and lymph node status or N-staging of colorectal cancer

Background

The purpose of this study is to examine the expression levels of lymphatic endothelial markers in colorectal cancer and to explore the correlation between the expression levels of markers and lymph node status.

Methods

Forty-seven paired fresh tumor tissues and para-cancerous tissues were collected from colorectal cancer patients who received surgical treatment between August 2015 and March 2016 in Cancer Hospital, Chinese Academy of Medical Sciences. Real-time quantitative PCR (RTQ–PCR) was used to check the expression levels of LYVE–1, VEGFR–3, Podoplanin, and Prox–1 in tumor and para-cancerous tissues.

Results

The positive expression rates of LYVE–1, VEGFR–3, Podoplanin, and Prox–1 in tumor tissues were 100, 93.6, 100, and 91.4%, but 100, 100, 100, and 87.2% in para-cancerous tissues. Comparing with para-cancerous tissues, tumor tissues had significantly lower expression levels of LYVE–1 (P < 0.001) and VEGFR–3 (P = 0.013) and higher levels of Podoplanin (P = 0.016) and Prox–1 (P = 0.078). There was no correlation between lymph node status and the expression level of LYVE–1 in tumor tissues (P = 0.354) or par-cancerous tissues (P = 0.617); similar results were found for VEGFR–3 (P = 0.631, 0.738), Podoplanin (P = 0.490, 0.625), and Prox–1 (P = 0.503, 0.174). Meanwhile, there was no correlation between N-staging and the expression level of LYVE–1 in tumor tissues (P = 0.914) or para-cancerous tissues (P = 0.784); similar results were found for VEGFR–3 (P = 0.493, 0.955), Podoplanin (P = 0.199, 0.370), and Prox–1 (P = 0.780, 0.234).

Conclusions

There was no correlation between expression levels of lymphatic endothelial markers and lymph node status; LYVE–1, VEGFR–3, Podoplanin, and Prox–1 could not be used for predicting the lymph node status or N-staging of colorectal cancer.

Expression of a novel endothelial marker, C-type lectin 14A, in epithelial ovarian cancer and its prognostic significance

OBJECTIVE

The purpose of this study was to evaluate microvessel density (MVD) as assessed by C-type lectin 14A (CLEC14A), which is a new marker for endothelial cells, and compare its expression to CD31 and CD105 in epithelial ovarian cancer (EOC).

METHODS

MVD was evaluated in tumors (n = 50) from patients with EOC who underwent primary surgery and in patients with EOC who received preoperative chemotherapy (n = 49) using immunohistochemistry with antibodies to CLEC14A, CD31 and CD105. The median duration of follow-up was 24.5 months (range 1-101 months). The effect of prognostic factors on event-free survival (EFS) and overall survival (OS) was assessed using the Cox regression model.

RESULTS

The amount of residual disease was found to be an independent prognostic factor in multivariate analysis with respect to EFS (P = 0.009) and OS (P < 0.001). The mean MVD of CLEC14A (MVD = 6), in tumors from patients who underwent primary surgery, was significantly lower than that of CD31 (MVD = 25, P < 0.0001) and CD105 (MVD = 11, P = 0.018). However, there was no significant correlation between MVD as detected by these markers and clinical outcome. There was no expression of CLEC14A in tumors from patients who received preoperative chemotherapy and the MVD of CD31 and CD105 was significantly reduced (P = 0.001 and 0.006, respectively) in this set of patients.

CONCLUSION

This study demonstrates MVD as detected by CLEC14A in EOC. Treatment with chemotherapy reduces tumor blood vessels significantly. We suggest that CLEC14A may be a more specific endothelial marker to assess tumor angiogenesis.

The role of intratumoral lymphovascular density in distinguishing primary from secondary mucinous ovarian tumors

OBJECTIVE

Ovarian mucinous metastases commonly present as the first sign of the disease and are capable of simulating primary tumors. Our aim was to investigate the role of intratumoral lymphatic vascular density together with other surgical-pathological features in distinguishing primary from secondary mucinous ovarian tumors.

METHODS

A total of 124 cases of mucinous tumors in the ovary (63 primary and 61 metastatic) were compared according to their clinicopathological features and immunohistochemical profiles. The intratumoral lymphatic vascular density was quantified by counting the number of vessels stained by the D2-40 antibody.

RESULTS

Metastases occurred in older patients and were associated with a higher proportion of tumors smaller than 10.0 cm; bilaterality; extensive necrosis; extraovarian extension; increased expression of cytokeratin 20, CDX2, CA19.9 and MUC2; and decreased expression of cytokeratin 7, CA125 and MUC5AC. The lymphatic vascular density was increased among primary tumors. However, after multivariate analysis, the best predictors of a secondary tumor were a size of 10.0 cm or less, bilaterality and cytokeratin 7 negativity. Lack of MUC2 expression was an important factor excluding metastasis.

CONCLUSIONS

The higher intratumoral lymphatic vascular density in primary tumors when compared with secondary lesions suggests differences in the microenvironment. However, considering the differential diagnosis, the best discriminator of a secondary tumor is the combination of tumor size, laterality and the pattern of expression of cytokeratin 7 and MUC2.

Vascular endothelial growth factor c promotes ovarian carcinoma progression through paracrine and autocrine mechanisms

Vascular endothelial growth factor C (VEGFC) has been reported to promote tumor progression in several tumor types, mainly through the stimulation of lymphangiogenesis and lymphatic metastasis. However, the expression and biological significance of the VEGFC/VEGF receptor (VEGFR)-3 pathway in ovarian cancer growth and dissemination are unclear, and have been investigated in this study. Soluble VEGFC was detected in the plasma and ascites of patients with ovarian carcinoma, and VEGFR3 expression was found in their tumor tissues. In human ovarian carcinoma xenograft models, high levels of soluble VEGFC in ascites and serum were detected, in association with disease progression, tumor burden, and volume of ascites. Peak VEGFC expression preceded para-aortic lymph node infiltration by HOC8 neoplastic cells. Histological detection of tumor cells in blood and lymphatic vessels indicated both hematogenous and lymphatic dissemination. Overexpression of VEGFC in the VEGFR3-positive and luciferase-expressing IGROV1 cells promoted carcinoma dissemination after orthotopic transplantation in the ovary of immunodeficient mice. In vitro, VEGFC released by the tumor cells stimulated tumor cell migration in an autocrine manner. Cediranib, an inhibitor of VEGFR1-3 and c-kit, inhibited in vivo metastasis of VEGFC-overexpressing IGROV1 and in vitro autocrine effects. These findings suggest that the VEGFC/VEGFR3 pathway acts as an enhancer of ovarian cancer progression through autocrine and paracrine mechanisms, hence offering a potential target for therapy.

The prognostic value of vascular endothelial growth factor in ovarian cancer: a systematic review and meta-analysis

OBJECTIVE

The prognostic role of vascular endothelial growth factor (VEGF) in ovarian cancer remains inconclusive. This meta-analysis aimed to explore the association between VEGF overexpression and survival outcomes in ovarian cancer patients.

METHODS

Studies were identified from PubMed and EMBASE searches performed on January 2nd, 2011. After careful review, survival data were extracted from eligible studies. A meta-analysis was performed to generate combined hazard ratio (HR) for progression-free survival (PFS) and overall survival (OS) in serum and tumor tissue studies.

RESULTS

Sixteen studies with 1111 patients were analyzed. Elevated serum VEGF was significantly associated with poor PFS [HR 2.46, 95% CI (1.84, 3.29)] and OS [HR 2.21, 95% CI (1.57, 3.13)]. No significant heterogeneity existed in serum studies. Similarly, tissue VEGF overexpression was associated with poor PFS [HR 1.63, 95% CI (1.09, 2.42)] and OS [HR 1.70, 95% CI (1.01, 2.87)]. However, significant heterogeneity was found in tissue studies, with I(2) of 44% for PFS and 64% for OS. Studies were stratified into subgroups by International Federation of Gynecology and Obstetrics (FIGO) stages. Subgroup analyses showed that high tissue VEGF was significantly associated with shorter PFS [HR 5.34, 95% CI (1.95, 14.59)] and OS [HR 6.13, 95% CI (2.47, 15.26)] in studies where predominantly early-stage patients were included, but not in studies with a majority of advanced-stage patients. Subgroup analysis was not performed in serum studies because all those studies enrolled more patients in advanced stages than early stages.

CONCLUSIONS

Overexpression of VEGF in primary tumor and serum associates with poor PFS and OS for patients with ovarian cancer. The association between high tissue VEGF level and poor prognosis exists in early stage patients, but not in advanced stage patients.

The adhesion molecule NCAM promotes ovarian cancer progression via FGFR signalling

Epithelial ovarian carcinoma (EOC) is an aggressive neoplasm, which mainly disseminates to organs of the peritoneal cavity, an event mediated by molecular mechanisms that remain elusive. Here, we investigated the expression and functional role of neural cell adhesion molecule (NCAM), a cell surface glycoprotein involved in brain development and plasticity, in EOC. NCAM is absent from normal ovarian epithelium but becomes highly expressed in a subset of human EOC, in which NCAM expression is associated with high tumour grade, suggesting a causal role in cancer aggressiveness. We demonstrate that NCAM stimulates EOC cell migration and invasion in vitro and promotes metastatic dissemination in mice. This pro-malignant function of NCAM is mediated by its interaction with fibroblast growth factor receptor (FGFR). Indeed, not only FGFR signalling is required for NCAM-induced EOC cell motility, but targeting the NCAM/FGFR interplay with a monoclonal antibody abolishes the metastatic dissemination of EOC in mice. Our results point to NCAM-mediated stimulation of FGFR as a novel mechanism underlying EOC malignancy and indicate that this interplay may represent a valuable therapeutic target.

Palliative surgery versus medical management for bowel obstruction in ovarian cancer

BACKGROUND

Ovarian cancer is the sixth most common cancer among women and is usually diagnosed at an advanced stage. Bowel obstruction is a common feature of advanced or recurrent ovarian cancer. Patients with bowel obstruction are generally in poor physical condition with a limited life expectancy. Therefore, maintaining their QoL with effective symptom control is the main purpose of the management of bowel obstruction.

OBJECTIVES

To compare the effectiveness and safety of palliative surgery (surgery performed to control the cancer, reduce symptoms and improve quality of life for those whose cancer is not able to be entirely removed) and medical management for bowel obstruction in women with ovarian cancer.

SEARCH STRATEGY

We searched the Cochrane Gynaecological Cancer Group Trials Register, The Cochrane Central Register of Controlled trials (CENTRAL), Issue 1 2009, MEDLINE and EMBASE up to February 2009. We also searched registers of clinical trials, abstracts of scientific meetings, reference lists of included studies and contacted experts in the field.

SELECTION CRITERIA

Studies that compared palliative surgery and medical interventions, in adult women diagnosed with ovarian cancer who had either full or partial obstruction of the bowel. Randomised controlled trials (RCTs) and non-RCTs that used multivariable statistical adjustment for baseline case mix were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed whether potentially relevant studies met the inclusion criteria, abstracted data and assessed risk of bias. One non-randomised study was identified so no meta-analyses were performed.

MAIN RESULTS

The search strategy identified 183 unique references of which 22 were identified as being potentially eligible on the basis of title and abstract. Only one study met our inclusion criteria and was included in the review. It analysed retrospective data for 47 women who received either palliative surgery (n = 27) or medical management with Octreotide (n = 20) and reported overall survival and perioperative mortality and morbidity. Women with poor performance status were excluded from surgery. Although six (22%) women who received surgery had serious complications of the operation and three (11%) died of complications, multivariable analysis found that women who received surgery had significantly (p < 0.001) better survival than women who received Octreotide, after adjustment for important prognostic factors. However, the magnitude of this effect was not reported. Quality of life (QoL) was not reported and adverse events were incompletely documented.

AUTHORS' CONCLUSIONS

We found only low quality evidence comparing palliative surgery and medical management for bowel obstruction in ovarian cancer. Therefore we are unable to reach definite conclusions about the relative benefits and harms of the two forms of treatment, or to identify sub-groups of women who are likely to benefit from one treatment or the other. However, there is weak evidence in support of surgical management to prolong survival.

Role of tumor-associated lymphatic endothelial cells in metastasis: a study of epithelial ovarian tumor in vitro

Tumor-associated lymphatic endothelial cells (TLEC) could play a key role in the process of tumor metastasis. The aim of this study was to investigate the effect of TLECs that were isolated from human epithelial ovarian tumor (EOT) on ovarian cancer cell line CAOV-3 in vitro. First, TLECs in EOT were detected by immunochemistry and flow cytometry, then marked by lymphatic endothelial cell (LEC) marker LYVE-1, isolated by magnetic beads, and cultured in vitro. The cells were identified by immunostaining of LEC markers LYVE-1, Prox-1, Podoplanin, VEGFR-3, and pan-endothelial cell marker CD31. TLECs from EOT can be detected, cultured, and identified in vitro successfully. The effects of TLECs on invasion and migration of CAOV-3 cells were investigated by 12-well Boyden chamber; the proliferation effect was studied by counting the Trypan blue exclusion cell number. Furthermore, changes in MMP-2/9 secreted by CAOV-3 cells treated with TLEC were shown using real-time PCR and zymography, and TIMP-1/2 was detected by real-time PCR. In vitro, TLECs can enhance invasion and migration of CAOV-3 cells, but have no significant effect on proliferation. It was clear that the expression of MMP-9 increased and TIMP-2 decreased in CAOV-3 cells treated by TLECs, and the increasing of MMP-9 was confirmed by zymography. TLECs from EOT can enhance migration and invasion of human ovarian carcinoma cell line in vitro, and the possible mechanism was through activation of MMP-9/TIMP-2.

Gonadotropin-regulated lymphangiogenesis in ovarian cancer is mediated by LEDGF-induced expression of VEGF-C

The risk and severity of ovarian carcinoma, the leading cause of gynecologic malignancy death, are significantly elevated in postmenopausal women. Ovarian failure at menopause, associated with a reduction in estrogen secretion, results in an increase of the gonadotropic luteinizing hormone (LH) and follicle-stimulating hormone (FSH), suggesting a role for these hormones in facilitating the progression of ovarian carcinoma. The current study examined the influence of hormonal stimulation on lymphangiogenesis in ovarian cancer cells. In vitro stimulation of ES2 ovarian carcinoma cells with LH and FSH induced expression of vascular endothelial growth factor (VEGF)-C. In vivo, ovariectomy of mice resulted in activation of the VEGF-C promoter in ovarian carcinoma xenografts, increased VEGF-C mRNA level, and enhanced tumor lymphangiogenesis and angiogenesis. Seeking the molecular mechanism, we examined the role of lens epithelium-derived growth factor (LEDGF/p75) and the possible contribution of its putative target, a conserved stress-response element identified in silico in the VEGF-C promoter. Using chromatin immunoprecipitation, we showed that LEDGF/p75 indeed binds the VEGF-C promoter, and binding is augmented by FSH. A corresponding hormonally regulated increase in the LEDGF/p75 mRNA and protein levels was observed. Suppression of LEDGF/p75 expression using small interfering RNA, suppression of LH and FSH production using the gonadotropin-releasing hormone antagonist cetrorelix, or mutation of the conserved stress-response element suppressed the hormonally induced expression of VEGF-C. Overall, our data suggest a possible role for elevated gonadotropins in augmenting ovarian tumor lymphangiogenesis in postmenopausal women.

Existence of the lymphatic system in the primate corpus luteum

To date, there have been no detailed studies on the lymphatic system in the primate corpus luteum (CL); early reports suggested that the presence of this "secondary circulation" in luteal tissue is species-dependant. Therefore, studies were designed to determine if (a) lymphatic vessels exist, and (b) recently discovered lymphangiogenic factors and their receptor are expressed in the macaque CL during the menstrual cycle. Immunohistochemistry (IHC) detected the lymphatic endothelial cell marker, lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1), in some endothelial cells and vessels within the ovarian stroma and theca layer of preovulatory follicles and in the CL. Dual fluorescent IHC demonstrated that LYVE1 co-localized with another lymphatic endothelial cell marker D2-40, but a blood vascular endothelial cell marker (von Willebrand Factor, VWF) was in different cells. The numbers and staining intensity of LYVE1-positive cells in the CL appeared to increase from early to mid luteal phase, and remained elevated thereafter. RT-PCR detected cDNA fragments for mRNAs encoding VEGFC, FIGF, and their receptor FLT4 in CL. Real-time PCR analyses revealed similar patterns of VEGFC and FLT4 expression during the luteal lifespan; mRNA levels increased (p < 0.05) from early to mid luteal phase and decreased (p < 0.05) by late luteal phase. In contrast, FIGF levels were elevated initially, declined (p < 0.05) at mid luteal phase, and then increased (p < 0.05) to very late luteal phase. The data strongly suggest that lymphatic vessels are present in the primate CL, and that the VEGFC/FIGF-FLT4 system regulates lymphangiogenesis and luteal structure-function during the menstrual cycle.

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.