Angiogenesis in breast cancer

Trihydroxyethyl Rutin Provides Neuroprotection in Rats With Cervical Spinal Cord Hemi-Contusion

Objective: To investigate the neuroprotective effects of trihydroxyethyl rutin in rats with cervical spinal cord hemi-contusion.

Methods: Adult male Sprague–Dawley rats were subjected to hemi-contusion at a stroke depth of 1.2 mm, and then intraperitoneally injected with 50 or 100 mg/kg trihydroxyethyl rutin per day for 12 weeks (T50 and T100 groups, respectively). Changes in somatosensory evoked potentials (SEPs), motor evoked potentials (MEPs), and behavior were continuously monitored. At 12 weeks post-injury, immunohistochemical staining was performed to assess changes in cervical spinal cord microvascular morphology. Magnetic resonance imaging (MRI) scans were performed to examine end-stage injury in the cervical spinal cord, and Eriochrome cyanine-stained slices of spinal cord tissue were evaluated for injury.

Results: There were no significant differences in biomechanical parameters among the spinal cord injury, T50 and T100 rat groups. At 3 days-post-injury, there was a significant decrease in grip strength. At 12 weeks post-injury, grip strength recovery was significantly better in the T50 and T100 groups than in the injury group. Compared with the injury group, the total limb placement frequency was significantly higher in the T50 group at 2, 4, 6, 10, and 12 weeks post-injury and in the T100 group at 2, 6, 8, and 10 weeks post-injury. Ipsilateral SEPs and MEPs were dynamic, increasing in latency and decreasing in amplitude in the injury compared with sham group. MRI scanning demonstrated that the coronal, sagittal, and transversal lesion areas were smaller in the T50 and T100 groups than in the injury group. Microvascular density showed a greater reduction in the injury group compared with the T50 and T100 groups. Eriochrome cyanine staining showed that the ipsilateral side, residual parenchyma, and gray matter areas were larger in the T50 and T100 groups than in the injury group.

Conclusion: Trihydroxyethyl rutin exhibits robust neuroprotective effects, improving limb motor function and nerve electrophysiological parameters after spinal cord injury, maintaining microvascular density, and reducing the area of injury and degree of demyelination.

Correlation of blood flow in hepatocellular carcinoma with serum high mobility group box protein 1 and microvascular invasion: A preliminary study

BACKGROUND

The occurrence and development of tumors are closely related to microcirculation and high mobility group box protein 1 (HMGB1) expression levels. It is very important to predict the microvascular invasion (MVI) of hepatocellular carcinoma (HCC) before operation.

AIM

To quantitatively analyze the blood flow characteristics of HCC by contrast-enhanced ultrasound (CEUS), and to explore the correlation of the blood flow with HMGB1 and MVI.

METHODS

Seventy-eight patients with HCC who underwent surgical resection were included. According to the postoperative pathological results, the patients were divided into either an MVI group (45 cases) or a non-MVI group (33 cases). All patients underwent CEUS 3 d before operation. The enhancement intensity (EI) and area under the curve (AUC) in HCC were measured by time-intensity curve analysis. Serum HMGB1 and vascular endothelial growth factor (VEGF) were measured by enzyme-linked immunosorbent assay. Microvessel density was measured after operation. The correlation between EI, AUC, and serum HMGB1 was analyzed.

RESULTS

EI and AUC in the MVI group were significantly higher than those in the non-MVI group (P < 0.05). Serum HMGB1 and VEGF were significantly higher than those of the non-MVI group (P < 0.05). EI and AUC were positively correlated with serum HMGB1 (r = 0.729 and 0.759, P < 0.05).

CONCLUSION

CEUS can quantitatively analyze the blood flow in HCC, and its blood flow parameters have a good correlation with serum HMGB1, which can provide reference for noninvasive assessment of MVI before operation.

Correlation between perfusion parameters of contrast-enhanced ultrasound and ANGPTL4 expression in hepatocellular carcinoma

BACKGROUND

Angiopoietin like protein 4 (ANGPTL4) is a secreted glycoprotein of the angiopoietin like protein family. Upregulation of ANGPTL4 expression can promote tumor angiogenesis. Contrast-enhanced ultrasound (CEUS) can objectively reflect tumor microcirculation perfusion and provide the hemodynamic information.

AIM

To investigate the correlation between ANGPTL4 expression and the perfusion parameters of CEUS in hepatocellular carcinoma (HCC).

METHODS

Eighty-four HCC patients (84 tumors) who underwent surgical resection at Zhejiang Xiaoshan Hospital were selected as study subjects. According to the ANGPTL4 expression status, the patients were divided into either an ANGPTL4 positive expression group (48 cases) or an ANGPTL4 negative expression group (36 cases). All patients underwent CEUS within 3 d before operation. The perfusion parameters were analyzed, including enhancement intensity (EI) and peak to time (TTP). Serum vascular endothelial growth factor (VEGF), ANGPTL4 expression, and microvessel density (MVD) were measured. The correlation between the perfusion parameters of CEUS and the ANGPTL4 expression was analyzed.

RESULTS

The EI in the ANGPTL4 positive expression group was significantly higher than that in the ANGPTL4 negative expression group (P < 0.05). The TTP in the ANGPTL4 positive expression group was significantly shorter than that in the ANGPTL4 negative expression group (P < 0.05). The MVD and VEGF in the ANGPTL4 positive expression group were significantly higher than those in the ANGPTL4 negative expression group (P < 0.05) There was a positive correlation between EI and ANGPTL4 expression in HCC (r = 0.753, P < 0.05), and a negative correlation between TTP and ANGPTL4 expression (r = -0.730, P < 0.05).

CONCLUSION

There is a certain correlation between the perfusion parameters of CEUS and ANGPTL4 expression in HCC. Thus, the perfusion parameters of CEUS can reflect the ANGPTL4 expression level in HCC in vivo and indirectly evaluate its angiogenesis.

Correlation between perfusion state and angiogenesis indexes in gastric cancer

BACKGROUND

Accurate evaluation of microcirculation perfusion in tumor tissue is of great significance for clinical treatment and prognosis evaluation. Contrast-enhanced ultrasonography (CEUS) is a highly sensitive means of monitoring microcirculation perfusion, which can objectively reflect the microcirculation perfusion state of tumor tissue and provide reliable hemodynamic information for clinical diagnosis and treatment.

AIM

To evaluate the perfusion status of gastric cancer (GC) by CEUS, and to explore the correlation between the perfusion status and the indexes of angiogenesis.

METHODS

Sixty-six patients with GC were selected as study subjects (GC group). All patients were examined by CEUS 3 d before operation. The enhanced intensity (EI) and time to peak (TTP) of GC and tumor-adjacent normal tissues were measured by time-intensity curve analysis. The levels of vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2) were measured by enzyme-linked immunosorbent assay (ELISA), and the microvessel density (MVD) was measured after operation. Seventy-two healthy volunteers were selected as a control group for comparative analysis.

RESULTS

The EI and MVD were significantly higher and the TTP was significantly shorter in GC tissue than in normal tissue (P < 0.05). VEGF and Ang-2 levels were significantly higher in the GC group than in the control group (P < 0.05). EI had a positive correlation with VEGF, Ang-2, and MVD (r = 0.85, 0.81, and 0.88, respectively; P < 0.05), and TTP had a negative correlation with VEGF, Ang-2, and MVD (r = -0.72, -0.73, and -0.86, respectively; P < 0.05).

CONCLUSION

CEUS can dynamically evaluate the perfusion status of GC, and CEUS blood flow parameters have a good correlation with VEGF, Ang-2, and MVD. CEUS can provide a noninvasive imaging method for clinical evaluation of the angiogenesis status of GC.

Three-Dimensional Changes in Cervical Spinal Cord Microvasculature During the Chronic Phase of Hemicontusion Spinal Cord Injury in Rats

BACKGROUND

The angioarchitecture of the spinal cord and microvascular changes after acute and subacute spinal cord injury (SCI) have been reported in rodents. Microvascular changes after chronic SCI have not been explored. We characterized three-dimensional microvascular changes during the chronic phase of cervical hemicontusion SCI in rats.

METHODS

At 12 weeks after 1.2-mm hemicontusion injury, microvascular parameters, including vascular volume, ratio of vascular volume to tissue volume, vascular number, and vascular separation, were measured at the epicenter and each cord segment, and the percentage and volume of spinal vessels with different diameters were measured by micro computed tomography at the injury segment.

RESULTS

The 1.2-mm hemicontusion injury applied a compressive force of 1.050 ± 0.103 N to the cord, resulting in a cavity and a significant decrease in microvasculature at the epicenter. The vascular volume, ratio of vascular volume to tissue volume, and vascular number of the C5 cord decreased by 40%, 38%, and 36% at 12 weeks after SCI, whereas vascular separation increased by 54% compared with the control group. In the chronic phase after SCI, the percentage and volume of spinal microvessels at the contusion segment decreased significantly (especially vessels with diameters <40 μm).

CONCLUSIONS

Blood supply to the cervical spinal cord is insufficient during the chronic phase of cervical hemicontusion SCI, especially in microvessels with diameters <40 μm. These results may provide a basis to explore microvascular changes of SCI during the chronic phase.

Value of micro-CT for monitoring spinal microvascular changes after chronic spinal cord compression

Neurological degeneration can occur after compression of the spinal cord. It is widely accepted that spinal cord compression leads to ischemic lesions and ultimately neurological dysfunction due to a narrowed spinal canal. Therefore, an in-depth understanding of the pathogenesis of spinal cord compression injury is required to help develop effective clinical interventions. In the present study, we propose a new method of quantitative 3D micro-CT to observe microvascular events in a chronic spinal cord compression rat model. A total of 36 rats were divided into two groups: sham control group (n = 12) and compressive spinal cord injury group (n = 24). Rats were scarified at four weeks after surgery. In each group, CD34 micro-vessel immunohistochemical staining was performed in half of the animals, while micro-CT scanning was performed in the other half. Microvessel density (MVD) was measured after immunohistochemical staining, while the vascular index (VI) was measured in 3D micro-CT. In comparison with sham control, abnormal somatosensory evoked potentials (SEP) can be seen in all 24 cases of the compression group, and VI shows the amount of microvessels reduced consistently and significantly (p < 0.01). A significant correlation is also found between MVD and VI (r = 0.95, p < 0.01). These data suggest that quantitative 3D micro-CT is a sensitive and promising tool for investigating microvascular changes during chronic compressive spinal cord injury.

Assessing breast cancer angiogenesis in vivo: which susceptibility contrast MRI biomarkers are relevant?

PURPOSE

There is an impending need for noninvasive biomarkers of breast cancer angiogenesis to evaluate the efficacy of new anti-angiogenic therapies in vivo. The purpose of this study was to systematically evaluate the sensitivity of in vivo steady-state susceptibility contrast-MRI biomarkers of angiogenesis in a human breast cancer model.

METHODS

Orthotopic MDA-MB-231 human breast cancer xenografts were imaged by steady-state susceptibility contrast-MRI at post-inoculation week 3 and post-inoculation week 5, followed by ex vivo whole tumor 3D micro-CT angiography. "Absolute" (i.e., measures of vascular morphology in appropriate units) and "relative" (i.e., proportional to measures of vascular morphology) MRI biomarkers of tumor blood volume, vessel size, and vessel density were computed and their ability to predict the corresponding micro-CT analogs assessed using cross-validation analysis.

RESULTS

All MRI biomarkers significantly correlated with their micro-CT analogs and were sensitive to the micro-CT-measured decreases in tumor blood volume and vessel density from post-inoculation week 3 to post-inoculation week 5. However, cross-validation analysis revealed there was no significant difference between the predictive accuracy of "absolute" and "relative" biomarkers.

CONCLUSION

As "relative" biomarkers are more easily computed from steady-state susceptibility contrast-MRI (i.e., without additional MRI measurements) than "absolute" biomarkers, it makes them promising candidates for assessing breast cancer angiogenesis in vivo.

Capillary permeability and extracellular volume fraction in uterine cervical cancer as patient outcome predictors: measurements by using dynamic MRI spin-lattice relaxometry

PURPOSE

To improve the outcome prediction of uterine cervical carcinoma by measuring the vascular permeability (k(ep)) and the extracellular volume fraction (v(e)) of the tumor from Dynamic T(1)- IRM Relaxometry.

MATERIALS AND METHODS

Twenty-six patients with proven cervical carcinoma were divided into good outcome and poor outcome groups. Classic tumor prognostic factors, the longest diameter L and the volume V of the tumor, were measured from morphologic MR images. The tumor parameters k(ep) and v(e) were determined from the relaxometry time-curve acquired during the contrast uptake after a bolus intravenous injection of an extracellular contrast agent.

RESULTS

All "small" tumors (L<35 mm or V<11 cm(3)) were good outcome with 100% sensitivity but a rather low specificity (36% and 43% for L and V, respectively). With regard to the physiopathological parameter k(ep), "large" tumors (L >or= 35 mm) can also be classified as good outcome on the condition that k(ep) >or= 2.2 min(-1) with 100% sensitivity and 89% specificity. Regarding the extracellular volume fraction (v(e)), no significant difference was observed between the two groups.

CONCLUSION

Measurement of the tumor vascular permeability might be useful to predict prognostic, to evaluate the treatment efficacy, and to adapt a proper therapy schedule.

Molecular biology of human gliomas

Human gliomas are the most common primary central nervous system neoplasm, and they are a complex, heterogeneous, and difficult disease to treat. In the past two decades, advances in molecular biology have revolutionized our understanding of the mechanism by which these neoplasms are initiated and progress. While surgery, radiation therapy, and chemotherapy have roles to play in the treatment of patients with gliomas; these therapies are self-limited because of the intrinsic resistance of glioma cells to therapy, and the diffusely infiltrating nature of the lesions. It is now known that malignant gliomas arise from a number of well-characterized genetic alterations and activations of oncogenes and inactivation of tumor suppressor genes. These genetic alterations disrupt critical cell cycle, growth factor activation, apoptotic, cell motility, and invasion pathways that lead to phenotypic changes and neoplastic transformation. Research in each of these fields has uncovered potential therapeutic targets that look promising for disease control. Gliomas can now be modeled with fidelity and reproducibility using several transgenic and knockout strategies. Transgenic mouse models are facilitating the testing of various therapeutic strategies in vivo. Finally, the recognition of the putative brain tumor stem cell, the tumor initiating cell in brain cancer, provides an enticing target through which we could eliminate the source of the brain tumor with increased efficacy and less toxicity to normal tissues. In this review, we provide an up-to-date discussion of the many of key technologies and tools that are being used in molecular biology to advance our understanding of the biological behavior of human malignant gliomas.

Immunohistochemical analysis of tumor angiogenic factors in human pituitary adenomas

Microvessel density (MVD) has been studied in a number of neoplasias, and apparently, there is a relationship between angiogenesis and tumor progression, response to treatment, and outcome. In pituitary adenoma, the association between MVD and vascular endothelial growth factor (VEGF) with tumor behavior has been described, but correlation with other angiogenic factors such as fetal liver kinase 1 (Flk-1) or proliferative markers is unknown. We investigated MVD, VEGF, and its receptor Flk-1 expression in 60 human pituitary adenomas: 13 growth hormone cell adenomas, 7 prolactin cell adenomas, 5 corticotroph cell adenomas, 2 thyrotroph cell adenomas, and 33 nonfunctioning adenomas (30 gonadotroph cell adenomas and 3 null cell adenomas). We performed immunohistochemistry for CD34, Ki-67, VEGF, and Flk-1. To evaluate MVD, we used 2 methods: the number of vessels per square millimeter and the Chalkley method. Immunohistochemistry results were correlated, as well as with clinicopathologic factors. Adenomas with higher MVD were thyrotroph cell adenomas (299.9 +/- 87.5), and those with lower MVD were prolactin cell adenomas (168.6 +/- 63.3; P = .45, analysis of variance). We found a trend toward higher MVD in the adenomas of older patients (P = .142), but no difference was found regarding sex, extrasellar extension, or Ki-67 (P > .05). However, extrasellar extension was nearly significant when the Chalkley method score was high (P = .056). Low expression of VEGF was seen predominantly in prolactin cell adenomas, and high in nonfunctioning adenomas, or in cases of older patients (P < or = .032). Flk-1 score correlated with VEGF (P = .006). High expression was observed in nonfunctioning adenomas, cases presenting at older ages, and with extrasellar extension (P < or = .022). Our study shows that VEGF and Flk-1 are widely expressed in pituitary adenomas, predominantly in nonfunctioning adenomas and those presenting at older ages. Moreover, Flk-1 is associated with a more aggressive phenotype, and it may have potential therapeutic interest.

Soluble Eph A receptors inhibit tumor angiogenesis and progression in vivo

The Eph family of receptor tyrosine kinases and their ligands, known as ephrins, play a crucial role in vascular development during embryogenesis. The function of these molecules in adult angiogenesis has not been well characterized. Here, we report that blocking Eph A class receptor activation inhibits angiogenesis in two independent tumor types, the RIP-Tag transgenic model of angiogenesis-dependent pancreatic islet cell carcinoma and the 4T1 model of metastatic mammary adenocarcinoma. Ephrin-A1 ligand was expressed in both tumor and endothelial cells, and EphA2 receptor was localized primarily in tumor-associated vascular endothelial cells. Soluble EphA2-Fc or EphA3-Fc receptors inhibited tumor angiogenesis in cutaneous window assays, and tumor growth in vivo. EphA2-Fc or EphA3-Fc treatment resulted in decreased tumor vascular density, tumor volume, and cell proliferation, but increased cell apoptosis. However, EphA2-Fc had no direct effect on tumor cell growth or apoptosis in culture, yet inhibited migration of endothelial cells in response to tumor cells, suggesting that the soluble receptor inhibited blood vessel recruitment by the tumor. These data provide the first functional evidence for Eph A class receptor regulation of pathogenic angiogenesis induced by tumors and support the function of A class Eph receptors in tumor progression.

Comparison and modulation of angiogenic responses by FGFs, VEGF and SCF in murine and human fibrosarcomas

The effects of angiogenic growth factors on the growth, vascular architecture and the downstream cytokine signaling of sarcomas are unknown. These are of potential great importance since sarcoma, like endothelium, is of mesodermal origin and therefore could grow in response to these factors. Three human sarcomas (leiomyosarcoma SK-LMS-1, liposarcoma SW872 and fibrosarcoma SW684) and one murine fibrosarcoma (KHT) were grown in nude and C3H/He mice, respectively. Tumor structural vessels, perfused vessels and hypoxia were quantified immunohistochemically. Fast-growing murine KHT tumors had a markedly higher number of structural vessels compared with the human sarcomas. In both murine and human sarcomas, approximately half of the total structural vessels were perfused, and the numbers of perfused vessels decreased with increasing tumor volume. In vitro, basal mRNA expression of several angiogenic growth factors and their receptors differed between two of the human sarcoma cell lines, SK-LMS-1 and SW872. Compared with SK-LMS-1, untreated SW872 cells had higher levels of mRNA expression for FGF11, FGF14, angiopoietin, CD105 and VEGFR1. Two sarcoma cell lines were also treated with 10 ng/ml of six angiogenic growth factors (FGF1, FGF2, FGF7, FGF10, VEGF and SCF) for 24 h, and mRNA expression of endogenous FGF family members (FGF1, FGF2, FGF10, FGF11, FGF13 and FGF14) were quantitatively measured using RNase protection at various times following treatments. Again, SW872 cells were more responsive to exogenous growth factor treatment compared with SK-LMS-1 cells in terms of the elevation of endogenous FGF mRNA expression. In the SW872 cells, all of the exogenous angiogenic growth factor treatments, except for VEGF, upregulated endogenous FGF1, FGF2 and FGF14 mRNA expression. The SK-LMS-1 cells, in contrast, only responded to exogenous FGF1, FGF7 and FGF10, but did not respond to VEGF.

Cloning of a cDNA encoding an isoform of human protein phosphatase inhibitor 2 from vascularized breast tumor

Using modified differential display, a gene fragment was identified as being over-expressed in human vascularized breast carcinoma when compare to its neighboring normal tissue. The differentially expressed pattern was confirmed by quantitative RT-PCR. Full-length cDNA was then cloned by both 3'-end RACE and 5'-end RACE. Analysis of the full-length cDNA of this gene reveals that this cDNA encodes an open reading frame of 615 bp, which is highly homologous to human protein phosphatase inhibitor-2, with 92% identity at the nucleotide level, and 89% identity at amino acid level. The results of this study suggest that this novel isoform of human protein phosphatase inhibitor-2 (nPPI-2) may be involved in the angiogenic switch during breast tumor development.

Low-dose oral methotrexate and cyclophosphamide in metastatic breast cancer: antitumor activity and correlation with vascular endothelial growth factor levels

BACKGROUND

Anticancer chemotherapy is thought to be effective by means of direct cytotoxicity on tumor cells. Alternative mechanisms of efficacy have been ascribed to several common anticancer agents, including cyclophosphamide (CTX), methotrexate (MTX), anthracyclines and taxanes, postulating an antiangiogenic activity.

PATIENTS AND METHODS

We evaluated the clinical efficacy and impact on serum vascular endothelial growth factor (VEGF) levels of low-dose oral MTX and CTX in patients with metastatic breast cancer. MTX was administered 2.5 mg bd on days 1 and 2 each week and CTX 50 mg/day administered continuously.

RESULTS

Sixty-four patients were enrolled, 63 were evaluable: Eastern Cooperative Oncology Group (ECOG) performance status 0-1, > or =2 sites of metastatic disease (n = 50 patients), progressive disease at study entry (n = 51), 1 regimen for metastatic disease (n = 32) and > or =2 regimens (n = 20). Among the 63 evaluable patients, there were two complete remissions (CR), 10 partial remissions (PR) for an overall response rate of 19.0% (95% CI 10.2% to 30.9%) and an overall clinical benefit (CR+ PR+ stable disease >24 weeks) of 31.7% (95% CI 20.6% to 44.7%). Grade > or =2 leucopenia was registered in only 13 patients. The median serum VEGF level for the subgroup of patients on treatment for at least 2 months decreased with treatment from 315 pg/ml (95% CI 245 to 435) at baseline to 248 pg/ml (95% CI 205 to 311) at 2 months (P <0.001). Both responders and non-responders showed similar reductions in serum VEGF (P = 0.78). After 6 months patients still on treatment had a median VEGF level of 195 pg/ml (95% CI 96 to 355), which was significantly lower than the median baseline values (P = 0.001).

CONCLUSIONS

Continuously low-dose CTX and MTX is minimally toxic and effective in heavily pretreated breast cancer patients. A drop in VEGF was associated with the treatment and so alternative hypotheses, other than that of direct toxicity on tumor cells, must be favored when trying to explain the anticancer effect.

Tamoxifen inhibits endothelial cell proliferation and attenuates VEGF-mediated angiogenesis and migration in vivo

INTRODUCTION

Angiogenesis is fundamental to tumour growth and vascular endothelial growth factor (VEGF) is one of the most potent proangiogenic cytokines known. We have previously demonstrated that tamoxifen reduces serum VEGF in certain cancer patients. We hypothesized that tamoxifen may attenuate the angiogenetic response to VEGF.

METHODS

Human dermal microvessel endothelial primary cell cultures (HMEC) were incubated with tamoxifen (1.25-5.0 microg) or vehicle. Cell proliferation was quantified using 5-bromo-2'-deoxyuridine (BrdU) labelling endothelial cell proliferation assay. The effect of oral tamoxifen (20 mg/day) on VEGF-mediated angiogenesis in vivo was assessed using a Matrigel angiogenesis assay in the Sprague-Dawley rat.

RESULTS

Tamoxifen (5.0 microg/ml) significantly reduced HMEC proliferation over 24 h when compared with cells treated with vehicle alone. Oral administration of tamoxifen in the rat (20 mg/day) significantly reduced endothelial cell proliferation and migration in response to VEGF.

CONCLUSION

Tamoxifen (5.0 microg/ml) reduces proliferation of a VEGF-dependent endothelial cell line in vitro. In vivo, orally administered tamoxifen reduces VEGF-mediated angiogenesis in the rat. These findings indicate that tamoxifen may directly inhibit the effect of VEGF on the endothelial cell, in addition to its previously described effect of reducing serum VEGF levels. This data supports a role for tamoxifen in modulation of the VEGF-dependent angiogenic response to surgical trauma, particularly as an adjuvant therapy for VEGF-dependent tumours.

Pathophysiologic basis of contrast enhancement in breast tumors

While the diagnostic benefits of gadolinium (Gd)-chelate contrast agents are firmly established in magnetic resonance imaging (MRI) of tumors, the pathophysiologic basis of the enhancement observed and its histopathologic correlate remained vague. Tumor angiogenesis is fundamental for growth and metastasis and also of interest in new therapeutic concepts. By correlative analysis of a) histology; b) vascular density (CD31); and c) vascular permeability (vascular permeability factor/vascular endothelial growth factor [VPF/VEGF]), we found a) significantly (P < 0.001) faster exchange rates in malignant compared with benign breast lesions; b) distinct differences in enhancement characteristics between the histologic types (invasive ductal carcinoma, invasive lobular carcinoma, and ductal carcinoma in situ); and c) dependence of enhancement kinetics on the VPF/VEGF expression. The pathophysiologic basis for the differences in contrast enhancement patterns of tumors detectable by MRI is mainly due to vascular permeability, which leads to more characteristic differences than vascular density. MRI is able to subclassify malignant breast tumors due to their different angiogenetic properties.

Tumor microvascularity has no independent prognostic significance for breast cancer

There is a continuing controversy regarding the value of estimating degree of intra-tumor vascularity to predict prognosis in breast cancer. In order to resolve this controversy, primary tumors from a cohort of 519 women with breast cancer were analysed to determine whether association exists between degree of vascularity and prognosis. Tumor vascularity was estimated by immunohistochemistry using a monoclonal antibody to the antigen CD31. The tumor area showing the highest degree of vascularity was chosen to score the number of microvessels per unit area. Issues such as the reproducibility of the microvascularity score and its association with tumor parameters including size, histological grade and hormone receptor levels were investigated. Although previously agreed criteria were used, consensus between two pathologists' estimations of the degree of vascularity was only moderate. There was no statistically significant association between tumor vascularity score and other currently established parameters of prognosis. After a median follow up of 71 months for axillary node negative patients, there was no association between tumor vascularity score and increased risk of relapse or death from breast cancer. In axillary node positive patients, tumor vascularity score was associated with increased risk of relapse and death from breast cancer. This association was not however independent of other established parameters of prognosis.

Molecular aspects of neuro-oncology

Detailed understanding of molecular events responsible for brain tumor growth is a prerequisite for the development of effective therapeutic modalities leading to improved prognosis and cure. Advances in molecular biology in the past decades have revolutionized our understanding of cancer, including brain tumors. We have learned that abnormal proliferation, inability of the cells to die and their potential to modify their tissue environment result from accumulation of genetic aberrations. This article reviews genetic mechanisms implicated in the pathogenesis of nervous system tumors, such as unactivation of tumor suppressor and replication error genes, generation of abnormal growth factor loops, alterations of apoptotic pathways and angiogenesis.