FGF18 as a potential biomarker in serous and mucinous ovarian tumors.

Fibroblast growth factor 18 (FGF18) has been suggested to play important roles in promoting progression of ovarian high-grade serous carcinoma. Our aim was to investigate FGF18 expression in the whole spectrum of serous and mucinous ovarian tumors, highlighting differences in expression within the adenoma-carcinoma sequence and differences between type I and type II tumors. We also aimed to test the prognostic significance of this expression and its relation to microvessel density (MVD). We evaluated the immunohistochemical expression of FGF18 and CD31 in 103 ovarian tumors and statistically analyzed their association with clinicopathological variables and patients' outcome. FGF18 score increased significantly within the adenoma-carcinoma sequence for serous and mucinous tumors. MVD increased significantly only among serous tumors. FGF18 and MVD correlated significantly (overall and among serous tumors only) and were significantly higher in type II than type I tumors. Cox regression models were built. Independent predictors could not be determined due to multicollinearity between the predictors. However, the combination of International Federation of Gynecology and Obstetrics (FIGO) stage, ovarian carcinoma type, and/or FGF18 score achieved the highest predictability of poor prognosis. FGF18 could play a role within the adenoma-carcinoma sequence in type I tumors and might modulate angiogenesis among serous tumors. Our findings further augment the differences between type I and type II tumors. The combination of FIGO stage, ovarian carcinoma type, and/or FGF18 score could predict poor prognosis among ovarian carcinoma patients. Our work identifies FGF18 in ovarian neoplasia as a promising field of research, although evaluation of the performance of the developed models is still needed.

Antitumor effect of FP3 on a patient-derived tumor tissue xenograft model of rectal carcinoma.

BACKGROUND/AIMS: FP3 is an engineered protein which contains the extracellular domain 2 of VEGF receptor 1 (Flt-1) and extracellular domain 3 and 4 of VEGF receptor 2 (Flk-1, KDR) fused to the Fc portion of human immunoglobulin G1. Previous studies demonstrated its antiangiogenic and antitumor effects in vitro and in vivo. METHODOLOGY: In this study, a PDTT xenograft model of rectal carcinoma was established for assessment of the antitumor activity of FP3. Xenografts were treated with FP3 or bevacizumab (Avastin). After tumor growth was confirmed, volume and microvessel density in tumors were evaluated. Levels of VEGF and PCNA in the tumor were examined by immunohistonchemical staining and western blotting. RESULTS: FP3 showed significant antitumor activity in the PDTT xenograft model of rectal carcinoma. The microvessel density in tumor tissues treated with FP3 was lower than that of the control. Antitumor activity of FP3 was similar to that of bevacizumab in the PDTT xenograft model of rectal carcinoma. CONCLUSIONS: This study indicated that FP3 could be used as an effective antiangiogenic and antitumor agent in treatment of colorectal carcinoma.

STAT5b as molecular target in pancreatic cancer--inhibition of tumor growth, angiogenesis, and metastases.

The prognosis of patients suffering from pancreatic cancer is still poor and novel therapeutic options are urgently needed. Recently, the transcription factor signal transducer and activator of transcription 5b (STAT5b) was associated with tumor progression in human solid cancer. Hence, we assessed whether STAT5b might serve as an anticancer target in ductal pancreatic adenocarcinoma (DPAC). We found that nuclear expression of STAT5b can be detected in approximately 50% of DPAC. Blockade of STAT5b by stable shRNA-mediated knockdown showed no effects on tumor cell growth in vitro. However, inhibition of tumor cell motility was found even in response to stimulation with epidermal growth factor or interleukin-6. These findings were paralleled by a reduction of prometastatic and proangiogenic factors in vitro. Subsequent in vivo experiments revealed a strong growth inhibition on STAT5b blockade in subcutaneous and orthotopic models. These findings were paralleled by impaired tumor angiogenesis in vivo. In contrast to the subcutaneous model, the orthotopic model revealed a strong reduction of tumor cell proliferation that emphasizes the meaning of assessing targets in an appropriate microenvironment. Taken together, our results suggest that STAT5b might be a potential novel target for human DPAC.

Adnexal mass vascularity assessed by 3-dimensional power Doppler: does it add to the risk of malignancy index in prediction of ovarian malignancy?: four hundred-case study.

The Risk of Malignancy Index (RMI) is used for the prediction of ovarian malignancy. It includes menopausal status, carbohydrate antigen 125 serum levels, and ultrasound criteria. Three-dimensional power Doppler (3-DPD) is a reproducible investigation for assessment of tumor vascularity, classifying vascularity to avascular, parallel, and chaotic patterns. In this study; 3-DPD was added to RMI for prediction of malignancy in 400 cases of ovarian masses. Sensitivity of RMI for prediction of malignancy was 88%, with a cutoff value of 202.5 at 95% confidence interval. Sensitivity of 3-DPD for prediction of malignancy was 75%, adding 3-DPD to RMI increased its sensitivity to 99%. Considering the pilot nature of the study, further studies are needed to corroborate such findings.

The reduction in pigment epithelium-derived factor is a sign of malignancy in ovarian cancer expressing low-level of vascular endothelial growth factor.

BACKGROUND: Angiogenesis is a critical factor in the progression of solid tumors and metastasis. The aim of this study was to characterise the roles of angiogenic and anti-angiogenic factors on ovarian cancer. METHODS: The expression levels of vascular endothelial growth factor (VEGF, angiogenic factor) and pigment epithelial growth factor (PEDF, anti-angiogenic factor) were measured by real-time polymerase chain reaction and Western blotting in ovarian tumors. Microvessel density (MVD) was evaluated by the total microvessel length in high-power field of tumor tissue preparations. RESULTS: MVD correlated with tumor malignancy. The tissues with the highest expression levels of VEGF (VEGF-H) were malignant tumors. The VEGF expression levels in some malignant tumors (VEGF-L) were as low as that in benign tumors. Therefore, the expression of PEDF was examined. The PEDF expression levels in VEGF-L malignant tumors were significantly lower than those in benign tumors. On the other hand, the PEDF expression levels in VEGF-H malignant tumor tissues were not significantly different from those in benign tumors. CONCLUSION: The reduction in PEDF expression levels may be, in part, responsible for tumor malignancy in VEGF-L ovarian tumors. Furthermore, PEDF may be a useful marker of malignancy in VEGF-L ovarian tumors.

Relationship between inducible nitric oxide synthase expression and angiogenesis in primary gallbladder carcinoma tissue.

AIM: To explore the relationship between angiogenesis and biological behaviors of primary gallbladder carcinoma (PGBC), the relationship between the expression of inducible nitric oxide synthase (iNOS) and biological behaviors of PGBC and its relationship with the expression of iNOS and angiogenesis of PGBC. METHODS: The expression of iNOS and micro-vessel density (MVD) were assessed by immunohistochemical method and image analysis system in 40 specimens of PGBC and in 8 specimens of normal gallbladder. The immunostaining results and related clinicopathologic materials were analyzed by statistical methods. RESULTS: MVD in PGBC was significantly higher than that in normal gallbladder tissue (46+/-14 vs 14+/-6, P<0.05), and was not related with age, gender, tumor size and histological type. MVD of poorly and undifferentiated tumor tissues was higher than that of moderately-differentiated and well-differentiated tumor tissues (52+/-9 vs 43+/-9 vs 33+/-6, P<0.01). MVD of Nevin IV and V stages was higher than that of Nevin I, II and III stages (52+/-8 vs 37+/-13, P<0.01). MVD of cases with lymphatic or liver metastasis was significantly higher than that without liver metastasis (55+/-6 vs 42+/-10, P<0.05)or lymphatic metastasis (53+/-8 vs 38+/-8, P<0.01). The positive level index (PLI) of iNOS in PGBC was 0.435+/-0.134, and was not related with age, gender, tumor size, histological type, differentiation and clinical stage of PGBC. The PLI of iNOS in cases with lymphatic metastasis was higher than that without lymphatic metastasis (0.573+/-0.078 vs 0.367+/-0.064, P<0.01). The PLI of iNOS in cases with liver metastasis was higher than that without liver metastasis (0.533+/-0.067 vs 0.424+/-0.084, P<0.05). There was a significant correlation between PLI of iNOS and MVD in PGBC (P<0.05). CONCLUSION: Angiogenesis of PGBC is significantly related to the biological behaviors of PGBC. The expression of iNOS is related to the biological behaviors of PGBC. The detection of MVD and the expression of iNOS in PGBC can be used as parameters to determine the degree of malignancy and prognosis.

Angiogenesis and extracellular matrix remodelling in bronchioloalveolar carcinomas: distinctive patterns in mucinous and non-mucinous tumours.

AIM: Bronchioloalveolar carcinomas (BACs) are rare primitive lung adenocarcinomas growing along the alveolar septum without stromal, vascular or pleural invasion. We report an immunohistochemical study of their vascular microenvironment. METHODS AND RESULTS: In three mucinous BACs (M-BAC) and three non-mucinous BACs (NM-BAC) we examined the following parameters in comparison with the normal lung: (i) constituents of the alveolar extracellular matrix; (ii) qualitative and quantitative changes of alveolar capillaries; and (iii) expression of vascular endothelial growth factor (VEGF) by tumour cells. In M-BAC, the alveolar matrix was unchanged compared with the normal parenchyma. Capillaries expressed normal alveolar endothelial markers and their average surface was calculated, as in normal lung, as 8%. VEGF was negative in tumour cells. In NM-BAC, the alveolar wall was thickened by deposits of fibronectin and type III collagen containing myofibroblasts and the basement membrane was disrupted. Capillaries did not retain alveolar endothelial markers and their surface was calculated as 19%. Tumour cells expressed high levels of VEGF. CONCLUSIONS: In contrast to NM-BAC, M-BAC do not modify the alveolar structure and seem to exploit the normal alveolar vascular bed to grow, without inducing neoangiogenesis. A better understanding of the mechanisms of growth of lung cancers may have implications for future anti-angiogenic therapeutic strategies.

Combretastatin A-1 phosphate potentiates the antitumour activity of cisplatin in a murine adenocarcinoma model.

BACKGROUND: The tubulin depolymerizing drug Combretastatin A-1 phosphate (CA1P), a water-soluble derivative of combretastatin A-1, has been recently shown to have a better efficacy in experimental models than the clinically active, close structural analogue, combretastatin A-4 phosphate (CA4P). Previous studies with CA4P in combination with standard anti-cancer agents have demonstrated improved efficacy relative to the standard agents. MATERIALS AND METHODS: In this study the synergistic effects of administering CA1P in combination with cisplatin (CPL) in a well-differentiated transplantable murine colon model (MAC 29) was evaluated. RESULTS: CA1P at 100 mgkg-1 significantly potentiated the anti-tumour effects of CPL. The effect with CPL was similar to that seen for CA1P at its maximum tolerated dose (MTD) alone. CONCLUSION: These data demonstrate that the combination of CA1P and CPL has significant preclinical antitumour activity against a transplantable murine adenocarcinoma model that is related to the antivascular effects of CA1P.

Thymidine phosphorylase-mediated angiogenesis regulated by thymidine phosphorylase inhibitor in human ovarian cancer cells in vivo.

Metastasis or progression of ovarian cancer cells is known to be due to the action of various angiogenic factors. We determined the expression of thymidine phosphorylase/platelet-derived endothelial cell growth factor (TP/PD-ECGF) and vascular endothelial growth factor (VEGF) in cell lines established from 3 serous adenocarcinomas, 3 clear cell carcinomas and 2 mucinous carcinomas of the human ovary. TP activity and the TP mRNA level were much higher in the serous adenocarcinoma cells than in the clear cells and mucinous carcinoma cells, and TP expression was extremely low in the clear cell carcinoma cells. Expression of VEGF mRNA was variable, but not significantly different between the 3 histological types of ovarian cancer. In vivo angiogenesis in the ovarian cancer cells was evaluated by the dorsal air sac assay and revealed that SHIN-3 and HRA serous adenocarcinoma cells, which have high levels of TP expression, induced angiogenesis, while KK clear cell carcinoma cells with low TP expression, did not. The degree of ovarian-cancer-induced angiogenesis seemed to be independent of expression of VEGF in the cells. To confirm that the serous adenocarcinoma-induced angiogenesis is dependent on TP levels, a potent and specific inhibitor of TP was administered orally to mice implanted with a chamber containing SHIN-3 or HRA cells. The TP inhibitor significantly inhibited the angiogenesis induced by the serous adenocarcinoma cells. These results suggest that the angiogenic potency of ovarian cancer cells differs with the histological type and is controlled by expression of TP/PD-ECGF, not by VEGF, and that TP-mediated angiogenesis may be the main factor responsible for progression or metastasis of ovarian serous adenocarcinomas.

Mucinous colon carcinomas with microsatellite instability have a lower microvessel density and lower vascular endothelial growth factor expression.

We determined the association between cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF) expression, microvessel density (MVD) and microsatellite instability (MSI) or the histological type in colon adenocarcinomas. Sixty-six cases were studied, 28 MSI+ and 38 MSI-. MSI phenotype was determined using polymerase chain reaction. MVD was assessed after CD31 staining in ten x400 fields (0.96 mm(2)) in the most vascularized areas. VEGF and COX-2 expression were studied by means of immunohistochemistry. MVD positively correlated with the levels of VEGF expression (P=10(-4)) and also with the levels of COX-2 expression (P=0.007). MVD and VEGF expression were lower in MSI+ carcinomas (P=0.002 and P=0.03 respectively). When mucinous tumors were excluded from the statistical analysis, the association between low MVD, low VEGF and MSI status disappeared (P=0.5, P=1, respectively). MSI+ mucinous carcinomas had a lower MVD and VEGF expression than other MSI+ carcinomas (P=0.008 and P=0.004, respectively) and MSI- mucinous carcinomas (P=0.01 and P=0.001, respectively). COX-2 expression was lower in medullary carcinomas (P=0.001). In conclusion, mucinous MSI+ colon carcinomas represent a special group of colon adenocarcinomas relating to angiogenesis, with a lower MVD and VEGF expression than both MSI- mucinous carcinomas and MSI+ non-mucinous carcinomas. A low COX-2 expression could be related to the medullary phenotype. However, this has to be confirmed in a larger series. Finally, the low MVD of MSI+ mucinous colon adenocarcinomas could participate in their overall better prognosis.

Differential inhibition of tumor angiogenesis by tie2 and vascular endothelial growth factor receptor-2 dominant-negative receptor mutants.

Tumor growth is angiogenesis-dependent. Current evidence suggests that vascular endothelial growth factor (VEGF), a major regulator of embryonic and hypoxia-mediated angiogenesis, is necessary for tumor angiogenesis. VEGF is expressed in tumor cells in vivo, and its tyrosine kinase receptors VEGFR-1 and VEGFR-2 are up-regulated in the tumor endothelium. A second endothelial cell-specific ligand/receptor tyrosine kinase system, consisting of the tie2 receptor, its activating ligand angiopoietin-1 and the inhibitory ligand angiopoietin-2, has been characterized. We have examined 6 human primary breast-cancer samples and 4 murine breast-cancer cell lines (M6363, M6378, M6444, M6468), transplanted into nude mice, by in situ hybridization and/or Northern analysis. Expression of angiopoietin-1, angiopoietin-2 and tie2 was compared to VEGF and VEGFR-2 expression. Human tumors expressed VEGFR-2 and tie2 but varied considerably in VEGF and angiopoietin-1/-2 expression. In the murine tumor models, we observed high heterogeneity of receptor and ligand expression. M6363 and M6378 tumors were analyzed in detail because they showed different expression of components of the tie2/angiopoietin signaling system. M6363 tumors expressed VEGF, VEGFR-2 and angiopoietin-2 but not tie2 or angiopoietin-1, suggesting activation of VEGFR-2 and inhibition of tie2 signaling pathways, whereas M6378 tumors expressed VEGF, VEGFR-2, tie2 and angiopoietin-1 but little angiopoietin-2, suggesting activation of both VEGFR-2 and tie2 signaling pathways. In vivo studies using truncated dominant-negative tie2 and VEGFR-2 mutants revealed inhibition of M6363 tumor growth by 15% (truncated tie2) and 36% (truncated VEGFR-2), respectively. In contrast, M6378 tumor growth was inhibited by 57% (truncated tie2) and 47% (truncated VEGFR-2), respectively. These findings support the hypothesis that tumor angiogenesis is dependent on VEGFR-2 but suggest that, in addition, tie2-dependent pathways of tumor angiogenesis may exist. For adequate application of angiogenesis inhibitors in tumor patients, analysis of prevailing angiogenesis pathways may be a prerequisite.

Interleukin 10 expression is correlated with thrombospondin expression and decreased vascular involvement in colon cancer.

Interleukin 10 (IL-10) is an immuno-suppressive cytokine produced by T-lymphocytes, and a regulatory molecule for angiogenesis in various cancers. We examined IL-10 gene expression in 53 colon cancer patients who underwent surgical resection. IL-10 gene expression was correlated with TSP1 and TSP2 gene expression (P=0.0049, P=0.0285). Colon cancer with IL-10 gene expression (19/53) showed significantly decreased venous involvement (P=0.0433). The mean vessel counts in the colon cancers with IL-10 gene expression were significantly lower than those without IL-10 gene expression (P<0.001). These results suggested that IL-10 stimulates angiostatic factor gene expression, and results in suppression of venous involvement.

Inducible nitric oxide synthase expression, apoptosis, and angiogenesis in in situ and invasive breast carcinomas.

In this investigation, we studied the expression of inducible nitric oxide synthase (iNOS) and its association to apoptosis and angiogenesis in 43 in situ and 68 invasive breast carcinomas. Its expression was studied immunohistochemically using a polyclonal iNOS antibody, and the staining was evaluated both in tumor and stromal cells. Apoptosis was detected by 3' end labeling of fragmented DNA (terminal deoxynucleotidyl transferase-mediated nick end labeling method). Vascularization was detected immunohistochemically using an antibody to the FVIII-related antigen, and calculated microvessel densities were determined. In addition to strong iNOS expression in stromal cells, iNOS positivity was observed in tumor cells in 46.5% of in situ and 58.8% of invasive carcinomas. In invasive carcinomas, there were more cases with iNOS positivity both in tumor and stromal cells compared to in situ carcinomas (0.007). The proportion of cases with iNOS-positive tumor cells increased in in situ carcinomas from grade I to III (20.0%, 46.2%, and 73.3%). In invasive ductal carcinomas, there were more cases with iNOS-positive tumor cells than with in situ carcinomas (P = 0.04). Carcinomas with both iNOS-positive tumor and stromal cells had a higher apoptotic index (P = 0.02) and a higher calculated microvessel densities index (P = 0.02). A high number of iNOS-positive stromal cells associated with metastatic disease (P = 0.05). The results show that breast carcinoma cells, in addition to stromal cells, express iNOS and are capable of producing NO. Carcinomas with iNOS-positive tumor and stromal cells have a higher apoptotic indices and increased vascularization, suggesting that iNOS contributes to promotion of apoptosis and angiogenesis in breast carcinoma. The association of the number of iNOS-positive stromal cells with metastatic disease might be attributable to stimulation of angiogenesis, resulting in a higher vascular density and consequently a higher probability for tumor cells to invade.

Vascular stroma formation in carcinoma in situ, invasive carcinoma, and metastatic carcinoma of the breast.

The generation of vascular stroma is essential for solid tumor growth and involves stimulatory and inhibiting factors as well as stromal components that regulate functions such as cellular adhesion, migration, and gene expression. In an effort to obtain a more integrated understanding of vascular stroma formation in breast carcinoma, we examined expression of the angiogenic factor vascular permeability factor (VPF)/vascular endothelial growth factor (VEGF); the VPF/VEGF receptors flt-1 and KDR; thrombospondin-1, which has been reported to inhibit angiogenesis; and the stromal components collagen type I, total fibronectin, ED-A+ fibronectin, versican, and decorin by mRNA in situ hybridization on frozen sections of 113 blocks of breast tissue from 68 patients including 28 sections of breast tissue without malignancy, 18 with in situ carcinomas, 56 with invasive carcinomas, and 8 with metastatic carcinomas. A characteristic expression profile emerged that was remarkably similar in invasive carcinoma, carcinoma in situ, and metastatic carcinoma, with the following characteristics: strong tumor cell expression of VPF/VEGF; strong endothelial cell expression of VPF/VEGF receptors; strong expression of thrombospondin-1 by stromal cells and occasionally by tumor cells; and strong stromal cell expression of collagen type I, total fibronectin, ED-A+ fibronectin, versican, and decorin. The formation of vascular stroma preceded invasion, raising the possibility that tumor cells invade not into normal breast stroma but rather into a richly vascular stroma that they have induced. Similarly, tumor cells at sites of metastasis appear to induce the vascular stroma in which they grow. We conclude that a distinct pattern of mRNA expression characterizes the generation of vascular stroma in breast cancer and that the formation of vascular stroma may play a role not only in growth of the primary tumor but also in invasion and metastasis.

VEGF, VEGFR-1, VEGFR-2, microvessel density and endothelial cell proliferation in tumours of the ovary.

VEGF is an angiogenic factor with potent endothelial cell (EC) proliferative actions. Our aim was to investigate whether expression of VEGF and its receptors and EC proliferation differ between ovarian tumour types and regions of the vasculature. VEGF, VEGFR-1, VEGFR-2 and EC proliferation were examined immuno-histochemically, and in situ hybridisation (ISH) studies of VEGF mRNA expression were performed and assessed in regions of high (HVD) and average (AVD) vessel density. VEGF immunostaining was significantly stronger in HVD regions of malignant compared with borderline serous tumours. VEGF immunostaining did not differ between tumour types; however, the percentage of VEGFR-1- and VEGFR-2-positive vessels was significantly lower in mucinous tumours. No differences were observed between HVD and AVD regions. VEGF ISH signal was observed in 2/7 borderline mucinous tumours, 8/14 malignant serous tumours and 5/13 benign tumours. The EC proliferation index was significantly lower in the HVD regions of serous relative to benign tumours. A negative correlation between VEGFR-1 immunostaining and microvessel density was observed in benign and serous tumours. However, EC proliferation index and VEGFR-1 positivity were positively correlated in benign tumours. Our results suggest that VEGF may play a role in the control of angiogenesis in serous and benign tumours but it does not appear to contribute to the previously reported higher microvessel density in mucinous tumours or to influence heterogeneity of microvessel density in ovarian tumours.

Increased microvessel density in mucinous compared with malignant serous and benign tumours of the ovary.

Microvessel density of benign, borderline and malignant ovarian tumours was studied immunohistochemically using antibodies to the endothelial cell markers CD31, CD34 and factor VIII-related antigen. Microvessel density was compared in tumours of different histological subtype, stage and patient outcome. CD31-immunostained sections were examined and regions of high and average microvessel density were selected. Identical regions were located on CD34- and factor VIII-related antigen-immunostained serial sections and microvessel counts obtained and converted to vessels mm(-2). CD31 and CD34 immunostaining revealed increased microvessel density in both the high and average vessel density regions of mucinous (222.4 +/- 24.8; 79.9 +/- 8.5) compared with serous (105.4 +/- 20.7; 33.3 +/- 6.8) and benign (84.4 +/- 19.4; 20.4 +/- 4.4) tumours (P < 0.001). CD31 and CD34 immunostaining also revealed increased microvessel density in early-stage mucinous tumours (234.6 +/- 28.2; 87.8 +/- 9.2) compared with that observed in both early- (72.8 +/- 15; 12.9 +/- 2.4) and late- (115.6 +/- 26.5; 29.8 +/- 8.5) stage serous tumours (P < 0.001). No differences in microvessel density in samples from patients with differing outcomes were observed (P > 0.05). Reduced factor VIII-related antigen compared with CD31 and CD34 immunostaining was observed in both borderline and malignant mucinous and serous tumours (P < 0.02) but not in benign tumours (P > 0.05). Our results contradict the putative association between increased microvessel density and poor prognosis and suggest that the level and control of angiogenesis may differ between ovarian tumour types.

Reduced vascular basement-membrane immunostaining in mucinous tumours of the ovary.

Tumour vasculature is heterogeneous, exhibiting a range of vessel densities and the vascular basement membrane (VBM) of tumour blood vessels may be fragmented or absent. Increased microvessel density (MVD) has been reported in mucinous ovarian tumours as compared with other histologic sub-types. We hypothesized that VBM immunostaining differs between regions of the ovarian tumour vasculature and between ovarian tumour types exhibiting different MVD. Serial sections from 56 ovarian tumours were immunostained using antibodies to the VBM components collagen IV, heparan sulphate proteoglycan and laminin, and the endothelial cell marker CD31. Regions of high and average MVD were selected, and the number of vessels positive for each VBM component were counted and expressed as a percentage of the number of CD31-positive vessels. The percentage of VBM-positive vessels did not differ between the high and average MVD regions of borderline or malignant, mucinous and serous tumours. The percentage of VBM-positive vessels in mucinous tumours was less than that observed in malignant and borderline serous tumours and benign tumours (p < 0.02). Possible explanations for these findings are (i) that VBM turnover is similar throughout the vasculature; (ii) that the VBM is present both during angiogenesis and in the newly formed vessels of high MVD regions; or (iii) that an alternative angiogenesis mechanism is utilized in different ovarian tumour types, or even between different regions of the same tumour.