The prognostic significance of tumor vascularization in patients with localized colorectal cancer

Can vascular endothelial growth factor and microvessel density be used as prognostic biomarkers for colorectal cancer? A systematic review and meta-analysis

Background. Vascular endothelial growth factor (VEGF) and microvessel density (MVD) are associated with greater incidence of metastases and decreased survival. Whether they can be used as prognostic indicators of colorectal cancer (CRC) is still controversial. Methods. The authors performed a meta-analysis using the results of a literature search of databases of PubMed and EMBASE, and the references of articles included in the analysis. Meta-analysis was performed using random effects model and hazard ratios (HRs) and 95% confidence intervals (CIs) as effect measures. Results. Twenty studies contributed to the analysis of VEGF, of which 16 were used for overall survival (OS) and 9 for disease-free survival (DFS). High VEGF levels has a relationship with unfavorable survival (OS: HR = 1.98, 95% CI: 1.30–3.02; DFS: HR = 2.10, 95% CI: 1.26–3.49) and a 4.22-fold increase in the rate of distant metastases. Analysis was performed on 18 studies for MVD; the results showed that patients with high MVD expression in tumors appeared to have poorer overall survival (HR = 1.39, 95% CI: 1.22–1.58) and were at a greater risk of having unfavorable clinical characteristics related to prognosis. Corresponding results were obtained from quantitative and/or qualitative analysis of clinicopathological. Conclusions. The meta-analysis demonstrates that VEGF and MVD can be used as prognostic biomarkers for CRC patients.

Regorafenib inhibits growth, angiogenesis, and metastasis in a highly aggressive, orthotopic colon cancer model

The combination of target-specific drugs like bevacizumab with chemotherapeutics has improved treatment efficacy in advanced colorectal cancer (CRC). However, the clinical prognosis of metastatic CRCs is still poor, and novel drugs are currently assessed with respect to their efficacies in patients with CRCs. In a phase III study, the multikinase inhibitor regorafenib (BAY 73-4506) has recently been shown to prolong survival of patients with CRCs after standard therapies failed. In the present study, the activity of regorafenib was investigated in comparison with the angiogenesis inhibitor DC101 in the highly aggressive, murine CT26 metastatic colon cancer model. While a treatment for 10 days with DC101 given at a dose of 34 mg/kg every third day significantly delayed tumor growth compared with vehicle-treated animals, regorafenib completely suppressed tumor growth at a daily oral dose of 30 mg/kg. Regorafenib also induced a stronger reduction in tumor vascularization, as longitudinally assessed in vivo by dynamic contrast-enhanced MRI (DCE-MRI) and confirmed by immunohistochemistry. In addition, regorafenib inhibited the angiogenic activity more strongly and induced a three times higher apoptosis rate than DC101. Even more important, regorafenib completely prevented the formation of liver metastases, whereas in DC101-treated animals, the metastatic rate was only reduced by 33% compared with the vehicle group. In addition, regorafenib significantly reduced the amount of infiltrating macrophages. These data show that the multikinase inhibitor regorafenib exerts strong antiangiogenic, antitumorigenic, and even antimetastatic effects on highly aggressive colon carcinomas indicative for its high potential in the treatment of advanced CRCs.

[Prognostic role of vascularisation and proliferation in rectal cancer with liver metastasis]

BACKGROUND

The present study was designed to provide an analysis of factors for angiogenesis and proliferation.

MATERIAL AND METHOD

We analyzed tumor tissues from 37 rectal cancer patients with concurrent or subsequent liver metastasis underwent preoperative radiotherapy, surgery and adjuvant chemotherapy. Immunohistochemistry was used for expression of proliferation (staining with anti-Ki67: MIB-1) and for detection of microvessel density (MVD, expressed by CD34). Clinicopathological findings were compared with outcome with emphasis to IHC.

RESULTS

A vascular enumeration and pN status and the time of presence of the metastases has shown prognostic role along with the factors above. Increased proliferative activity of the tumor as expressed by MIB-1 staining has no prognostic value, similarly to the localization of tumor, gender, age or grading.

SUMMARY

Different prognostic and predictive factors in colorectal cancer have been reported. Higher pN status and tumor vascularisation has been linked to poor prognosis in overall survival and tumor recurrence.

A stochastic model of tumor angiogenesis

Angiogenesis is a prerequisite for the growth, invasion and metastasis of solid tumors. The aim of this study was to investigate the changes of microvessel densities in tumor with a method of probability. We showed that the stages of tumor angiogenesis may follow a probabilistic pattern compatible with Markov chain and this could be of prognostic importance. The system was simulated with 10,000 patients in order to show the applicability of this method. This approach may improve classification schemes and perhaps make diagnosis and treatment more individualized to patients.

Evaluation of colon cancer vascularity by flash echo imaging

OBJECTIVE

Tumor vascularity is strongly related to the prognoses of patients with various malignant primary tumors, including colorectal cancer. The aim of this study was to confirm the usefulness of harmonic flash echo imaging (H-FEI) for the preoperative evaluation of tumor vascularity in colorectal cancer by comparison with CD34 staining of resected specimens.

MATERIAL AND METHODS

Seventeen patients undergoing surgical resection for advanced colorectal cancer (9 M, 8 F) were enrolled in this study. An ultrasound system transmitting ultrasound pulses at 2.3 MHz and receiving them at 4.6 MHz (second harmonic) was used for H-FEI. After intravenous injection of ultrasonic contrast medium (SHU 508A), intermittent harmonic scanning was carried out for 120 s at intervals of 4 s. On the tumor image of the strongest enhancement in each patient, 5 regions of interest were taken to decide the mean echo intensity of the tumor. Immunohistochemistry using antibodies against CD34 was carried out on resected specimens. The mean microvessel density was decided by counting microvessels on 5 fields (x 400) of CD34-stained specimens.

RESULTS

The mean value of H-FEI intensity was 5.44+/-1.10, and the mean microvessel count with CD34 staining was 35.0+/-7.95. A significant positive linear correlation was observed between the intensity of H-FEI determined preoperatively and the microvessel count in CD34-stained specimens (r=0.741, p=0.0006).

CONCLUSION

Vascularity of colon cancer can be evaluated non-invasively using H-FEI.

[Assessment of angiogenesis expression and its relationship with prognosis of colorectal cancer by conventional and computer-assisted histopathological image analysis]

PURPOSE

To quantify the degree of angiogenesis by conventional method (microvessel density, MVD) and computerized method (endothelial area, EA), and to evaluate their relationships with the prognosis of patients operated on for colorectal adenocarcinoma.

METHODS

Tumoral angiogenesis was studied by means of an immunohistochemical technique, using CD 34, on 126 patients; to quantify the angiogenesis, MVD (defined as number of microvessels per mm(2)) and EA measurement (defined as the area occupied by EA in the microscope field). A computerized method, IMAGELab software was utilized to quantify endothelial area.

RESULTS

The mean number of microvessels was 128.6 MV/mm(2) (SD = 44.5) and the mean EA was 4.3% (SD = 2.1). The Pearson method demonstrated a low correlation coefficient between MVD and EA (r = 0.429). No relationship between MVD and EA was observed with regard to relapse-free interval and overall survival.

CONCLUSION

The histological analysis of angiogenesis expression in patients with colorectal adenocarcinoma can be performed either by computer-assisted image analysis of endothelial area or by conventional microvessels counting. Both methods did not show any significant relationship between these angiogenesis parameters with relapse-free interval and overall survival.

Angiogenesis in colorectal cancer: prognostic and therapeutic implications

Angiogenesis is important for tumor growth and metastasis. This account reviews the clinicopathological studies conducted in the field of angiogenesis in colorectal cancer, the methods of assessing vascular-related characteristics in tissue sections and provides a background for the usefulness of antiangiogenic policies along with chemotherapy and radiotherapy. Highly angiogenic colorectal tumors are associated with aggressive histopathological features and poor patients' survival. Similarly, factors stimulating angiogenesis, such as vascular endothelial growth factor (VEGF), thymidine phosphorylase (TP), and others, are commonly related to increased vascular density (VD) and, therefore, to an unfavorable clinical course. Anti-VEGF agents have improved prognosis in patients with metastatic colorectal cancer, when added to standard chemotherapy. It is expected that, in addition to adjuvant chemotherapy and radiotherapy, agents blocking the stimulatory effect of VEGF on endothelial cells would prove beneficial to the patient.

Microvessel density and VEGF expression are prognostic factors in colorectal cancer. Meta-analysis of the literature

We performed a meta-analysis of all published studies relating intratumoural microvessel density (MVD) (45 studies) or vascular endothelial growth factor (VEGF) expression (27 studies), both reflecting angiogenesis, to relapse free (RFS) and overall survival (OS) in colorectal cancer (CRC). For each study, MVD impact was measured by risk ratio between the two survival distributions with median MVD as cutoff. Eleven studies did not mention survival data or fit inclusion criteria, six were multiple publications of same series, leaving 32 independent studies for MVD (3496 patients) and 18 for VEGF (2050 patients). Microvessel density was assessed by immunohistochemistry, using antibodies against factor VIII (16 studies), CD31 (10 studies) or CD34 (seven studies). Vascular endothelial growth factor expression was mostly assessed by immunohistochemistry. Statistics were performed for MVD in 22 studies (the others lacking survival statistics) including nine studies (n = 957) for RFS and 18 for OS (n = 2383) and for VEGF in 17 studies, including nine studies for RFS (n = 1064) and 10 for OS (n = 1301). High MVD significantly predicted poor RFS (RR = 2.32 95% CI: 1.39-3.90; P < 0.001) and OS (RR = 1.44; 95% CI: 1.08-1.92; P = 0.01). Using CD31 or CD34, MVD was inversely related to survival, whereas it was not using factor VIII. Vascular endothelial growth factor expression significantly predicted poor RFS (RR = 2.84; 95% CI: 1.95-4.16) and OS (RR=1.65; 95% CI: 1.27-2.14). To strengthen our findings, future prospective studies should explore the relation between MVD or VEGF expression and survival or response to therapy (e.g. antiangiogenic therapy). Assessment of these angiogenic markers should be better standardised in future studies.

Molecular mechanisms and targeting of colorectal cancer

Targeted therapies that are approved for metastatic colorectal cancer are divided into two groups: those affecting vascular endothelial growth factor (VEGF) known to interrupt tumor growth and metastasis (also called neo-angiogenesis), and agents that affect the tumor directly by interrupting the epidermal growth factor (EGF) and its receptor. Anti-angiogenic VEGF therapies are divided into two categories: one affecting the VEGF ligand, such as bevacizumab, and those that inhibit the VEGF receptor, such as PTK/ZK. Epidermal growth factor receptor (EGFR) therapies are divided into monoclonal antibodies that affect EGFR, such as cetuximab, and EGFR tyrosine kinase inhibitors, such as gefitinib. Both VEGF and EGFR areas of treatment have shown promising efficacy in first-line, combination therapy settings. Future targeted therapeutic strategies include gene profiling, combinations of capecitabine and oxaliplatin, with bevacizumab and/or cetuximab therapies.

Inclusion of Vasculature-Related Variables in the Dukes Staging System of Colon Cancer

PURPOSE

The Dukes stage is used to stratify colorectal cancer patients into groups of different prognosis and need of adjuvant radiotherapy and chemotherapy. However, approximately 80% of patients with Dukes stage C colorectal cancer receive cytotoxic therapy without any expected benefit, for such patients would either not relapse without adjuvant therapy or they would inevitably do so because of tumor resistance to the available regimens. On the other hand, as 20% of Dukes stage B patients would relapse after surgery, adjuvant therapy could improve their survival. Improvement of the Dukes stage predictive accuracy is necessary to better assign patients for adjuvant therapies, especially nowadays when antiangiogenic agents are being incorporated in the clinical practice.

PATIENTS AND METHODS

In this study, we examined the prognostic role of Dukes staging system in parallel with three vasculature-related variables (vascular invasion, tumor angiogenic activity, and vascular survival ability) in a series of 130 stage B/C patients with colorectal cancer treated with surgery alone (without adjuvant radiotherapy or chemotherapy).

RESULTS

Inclusion of vasculature-related variables in the Dukes staging system significantly improved the prognostic categorization of patients, identifying subgroups of B-stage and C-stage patients with an up to 40% and 60% 5-year survival difference, respectively.

CONCLUSIONS

Preliminary results show that the prognostic value of Dukes staging system is significantly improved after taking into account vasculature-related variables, which may be useful in stratifying patients for adjuvant therapies, highlighting also subgroups that may benefit the most from antiangiogenic agents.

Tumour angiogenesis and mast cell density in the prognostic assessment of colorectal carcinomas

BACKGROUND

Tumour angiogenesis is essential for the growth, invasion and metastasis of solid tumours. There are several lines of evidence that the mast cells play an important role in tumour angiogenesis.

AIMS

The study focused to determine the correlation between the microvessel and mast cell densities, and to evaluate whether tumour angiogenesis and mast cell density could predict recurrence following curative surgery in patients with colorectal carcinomas.

PATIENTS

Microvessel and mast cell densities were investigated in tumour specimens from 60 patients with colorectal carcinoma.

METHODS

Microvessels were stained by immunohistochemical method using a monoclonal antibody anti-CD34. The routine Giemsa blue staining method was used to assess the mast cells. Microvessels and mast cells were counted in a x400 field.

RESULTS

The mean microvessel and mast cell counts were higher in patients with recurrence compared with those patients who were disease-free for at least 24 months (p<0.001). The Spearman's correlation coefficient revealed a significant correlation between mast cell and microvessel counts in colorectal carcinomas (r=0.684; p<0.001). Kaplan-Meier plots of survival showed that the high microvessel (>28) and mast cell (>6) counts correlated with a shorter disease-free survival (p=0.0003 and p=0.0013, respectively). Multivariate analysis showed that the depth of penetration (T4 versus T2) (p=0.004), liver metastasis (p=0.04) and microvessel density (p=0.003) were independent predictors of recurrence. In multivariate analysis, mast cell density did not reach significance.

CONCLUSIONS

Our results suggest that the microvessel density of the primary tumour may be an important independent predictor of tumour recurrence and time to recurrence in colorectal carcinomas. The significant correlation between mast cell and microvessel counts suggest that the mast cells may have a role in tumour progression via promoting angiogenesis.

Allelic loss of a common microsatellite marker MYCL1: a useful prognostic factor of poor outcomes in colorectal cancer

PURPOSE

Allelic loss involving chromosome arms 5q, 8p, 17p, and 18q is commonly detected in colorectal cancer (CRC). The short arm of chromosome 1 is also frequently affected in a whole range of cancer types, including CRC. Our aim in the present study was to determine whether allelic losses on 1p were likely to be of much value in predicting the prognosis of CRC cases.

EXPERIMENTAL DESIGN

Genomic DNA was prepared from tumor and corresponding normal tissue specimens from 90 patients who had undergone curative resection for CRC. Loss of heterozygosity (LOH) on chromosome arms 1p, 2p, 5q, 7q, 8p, 17p, 17q, and 18q was examined using 14 microsatellite markers, and possible correlations between LOH and clinicopathological factors (including tumor recurrence and patient survival) were investigated. LOH at the MYCL1 microsatellite marker at 1p34 was detected in 12 of 74 (16.2%) patients who were informative for this marker.

RESULTS

After controlling for tumor stage and gender and excluding findings for patients with remote metastasis, we found that patients who were positive for LOH at MYCL1 were 31 times more likely to experience recurrence than those who were negative for LOH at this locus (95% confidence intervals, 2.27- infinity; P = 0.04). There were indications of a similar tendency for LOH at the 14-3-3-sigma-TG microsatellite marker at 1p35, but we could find no evidence of a significant association between LOH at this site and tumor recurrence or patient survival. We were also unable to detect significant association between LOH at the various sites on 2p, 5q, 7q, 8p, 17p, 17q, and 18q and either tumor recurrence or patient survival.

CONCLUSIONS

CRC patients whose tumors exhibited LOH at MYCL1 at chromosome 1p34 were likely to have a poor prognosis, suggesting that this marker may have clinical relevance.

Clinical significance of angiogenesis in gastrointestinal cancers: a target for novel prognostic and therapeutic approaches

OBJECTIVE

To review the current data on the prognostic and therapeutic implications of tumor angiogenesis in gastrointestinal cancers.

SUMMARY BACKGROUND DATA

Numerous studies have evaluated the prognostic value of tumor angiogenesis and the potential role of antiangiogenic therapy in various gastrointestinal cancers.

METHODS

A Medline literature search was conducted using "angiogenesis" or the names of various angiogenic factors in combination with the names of gastrointestinal cancers as the key words.

RESULTS

Several studies have demonstrated a significant prognostic impact of tumor microvessel density and tumor expression of angiogenic factors, in particular vascular endothelial growth factor (VEGF), in various gastrointestinal cancers. A few studies have suggested that circulating VEGF might be a useful prognostic marker. However, results were not consistent across all studies and were limited by the retrospective nature of most studies. Antiangiogenic therapy has been shown to be effective against all common gastrointestinal cancers in preclinical studies, but currently there are few clinical data with regard to antiangiogenic therapy in gastrointestinal cancers.

CONCLUSIONS

There is mounting evidence to suggest that assessment of tumor angiogenesis might provide a novel approach of prognostication in patients with gastrointestinal cancers. However, current results from retrospective studies need to be validated by prospective studies. Antiangiogenic therapy is a promising strategy of cancer treatment that might be particularly useful in combination therapy for unresectable cancers or as an adjuvant therapy for resectable tumors.

Angiogenesis and dendritic cell density are not correlated with metachronous distant metastasis in curatively operated rectal cancer

BACKGROUND AND AIMS

Apart from surgery, treatment of rectal cancer increasingly involves the use of (neo-)adjuvant strategies. To optimize the selection process for these therapy regimens, especially in the field of cellular and molecular biology, new prognostic factors additional to the established TNM system are being investigated.

PATIENTS AND METHODS

Two groups of patients ( n=2x85) with rectal carcinoma curatively treated by surgery alone were studied retrospectively (median follow-up 6.1 years). To exclude the effect of the surgeon only patients free of locally recurrent disease were selected. Patient groups were matched for age, gender, UICC stage, and year of operation (1982-1991) and differed only in subsequent metachronous distant metastatic spread, i.e., the criterion to be studied. The factors investigated in uni- and multivariate analysis were angiogenesis, density of dendritic cells, grading, venous invasion, and lymphatic invasion.

RESULTS

Grading invariably proved to be the only significant prognostic factor. In univariate analysis the absence of venous invasion was also correlated significantly with increased disease-free survival.

CONCLUSION

Angiogenesis and dendritic cell density are not prognostic factors for metachronous distant metastasis in rectal cancer and therefore cannot serve as selection parameters for adjuvant therapy.

Anti-angiogenic effect of silymarin on colon cancer LoVo cell line

OBJECTIVE

This study was designed to evaluate the anti-angiogenic effect of silymarin (SM) and its major pure component silibinin (SB), and also thalidomide (TH).

MATERIALS AND METHODS

A modified in vitro system using a coculture of endothelial (EA.hy 926) and colon cancer (LoVo) cell lines was adopted in this study.

RESULTS

In cytotoxicity assay, SM/SB/TH concentrations causing 20% (IC(20)) inhibition of cellular growth were 41.8 microg/ml/0.22 mM/0.088 mM for EA.hy 926 cells, and 16.1 microg/ml/0.12 mM/0.099 mM for LoVo cells, respectively. All 3 drugs showed concentration dependent inhibition of migration and differentiation assay. The IC(50) inhibiting chemotaxis migration of EA.hy 926 towards LoVo by SM/SB/TH was 1.15 microg/ml/0.66 microM/1.98 microM, respectively. In differentiation assay, SM/SB/TH inhibited in vitro capillary tube formation by 50% at 1.25 microg/ml/2.6 micro/6.3 microM, respectively. In an analysis of vascular endothelial growth factor secreted by LoVo cells, SM/SB/TH decreased 50% secretion at 6.52 microg/ml/6.6 microM/131.7 microM, respectively.

CONCLUSION

SM/SB has a strong anti-angiogenesis effect on the colon cancer cell line, and this might provide an alternative treatment option for anti-cancer treatment.

Clinical significance of angiogenesis in gastrointestinal cancers: a target for novel prognostic and therapeutic approaches

OBJECTIVE

To review the current data on the prognostic and therapeutic implications of tumor angiogenesis in gastrointestinal cancers.

SUMMARY BACKGROUND DATA

Numerous studies have evaluated the prognostic value of tumor angiogenesis and the potential role of antiangiogenic therapy in various gastrointestinal cancers.

METHODS

A Medline literature search was conducted using "angiogenesis" or the names of various angiogenic factors in combination with the names of gastrointestinal cancers as the key words.

RESULTS

Several studies have demonstrated a significant prognostic impact of tumor microvessel density and tumor expression of angiogenic factors, in particular vascular endothelial growth factor (VEGF), in various gastrointestinal cancers. A few studies have suggested that circulating VEGF might be a useful prognostic marker. However, results were not consistent across all studies and were limited by the retrospective nature of most studies. Antiangiogenic therapy has been shown to be effective against all common gastrointestinal cancers in preclinical studies, but currently there are few clinical data with regard to antiangiogenic therapy in gastrointestinal cancers.

CONCLUSIONS

There is mounting evidence to suggest that assessment of tumor angiogenesis might provide a novel approach of prognostication in patients with gastrointestinal cancers. However, current results from retrospective studies need to be validated by prospective studies. Antiangiogenic therapy is a promising strategy of cancer treatment that might be particularly useful in combination therapy for unresectable cancers or as an adjuvant therapy for resectable tumors.

Microvessel densities and microvascular architecture in colorectal carcinomas and their liver metastases: significant correlation of high microvessel densities with better survival

AIMS

Microvessel densities in cancers have been shown to be a prognostic factor for some types of cancer. For colorectal cancer, however, the situation is far from clear.

METHODS

A consecutive series of 173 colorectal carcinomas was investigated, and to these were added 55 liver metastases originating from colorectal cancer. Microvessels were counted in hotspots (factor VIII immunostaining, 0.74 mm2). The capillary architecture was scored according to the degree of order and envelopment of the neoplastic glands. Endothelial proliferation was determined by factor VIII/Ki67 double labelling.

RESULTS

Mean microvessel densities were 51.8 for colorectal carcinomas (range 8-140) and 31.9 for liver metastases (range 3-101). Stratification according to stage, depth of infiltration and nodal involvement showed a significant inverse relation with increase. Mean microvessel densities in primaries were significantly higher than in metastases. Kaplan-Meier analysis showed a significantly higher cancer-specific survival for high microvessel densities (median as cut-off) and for a more ordered microvascular architecture. Endothelial proliferation in carcinomas was significantly higher than in normal mucosa.

CONCLUSIONS

Contrary to other types of cancer, for colorectal cancer high microvessel densities confer good rather than poor prognosis. We hypothesize that neoangiogenesis, though extant in colorectal cancer, is not rate-limiting in the metastatic cascade.

Angiogenic effects of interleukin 8 (CXCL8) in human intestinal microvascular endothelial cells are mediated by CXCR2

Angiogenesis plays a critical role in metastasis and tumor growth. Human tumors, including colorectal adenocarcinoma, secrete angiogenic factors, inducing proliferation and chemotaxis of microvascular endothelial cells, eventually leading to tumor neovascularization. The chemokine interleukin 8 (IL-8; CXCL8) exerts potent angiogenic properties on endothelial cells through interaction with its cognate receptors CXCR1 and CXCR2. As CXCR1 and CXCR2 expression is differentially regulated in tissue-specific endothelial cells and effects of IL-8 on intestinal endothelial cells are not defined, we characterized the potential IL-8-induced angiogenic mechanisms in primary cultures of human intestinal microvascular endothelial cells (HIMEC) and IL-8 receptor expression in human intestinal microvessels. CXCR1 and CXCR2 expression on HIMEC were defined using reverse transcriptase-PCR, immunohistochemistry, flow cytometry, and Western blot analysis. IL-8-induced downstream signaling events were assessed using immunoblot analysis and immunofluorescence. The angiogenic effects of IL-8 on HIMEC were determined using proliferation and chemotaxis assays. HIMEC responded to IL-8 with rapid stress fiber assembly, chemotaxis, enhanced proliferation, and phosphorylation of extracellular signal-regulated protein kinase 1/2 (ERK 1/2). HIMEC express CXCR2, but not CXCR1. Neutralizing antibodies to CXCR2 diminished IL-8-induced chemotaxis and stress fiber assembly. Specific inhibitors of ERK 1/2 and phosphoinositide 3-kinase abrogated endothelial tube formation and IL-8-induced chemotaxis in HIMEC. IL-8 elicits angiogenic responses in microvascular endothelial cells isolated from human intestine by engaging CXCR2. We confirmed tissue expression of CXCR2 in human intestinal microvessels. Supported by the notion that malignant colonic epithelial cells overexpress IL-8, CXCR2 blockade may be a novel target for anti-angiogenic therapy in colorectal adenocarcinoma.

Angiogenesis in normal and neoplastic pituitary tissues

Angiogenesis, or the formation of new blood vessels, is a dynamic process needed for embryogenesis, post-natal growth, morphogenesis, tumorigenesis, and for other biological processes. Angiogenesis is very important for tumor development and progression. This review examines the activators and inhibitors of angiogenesis with emphasis on the pituitary gland and pituitary neoplasms. Some of the proteins regulating angiogenesis in pituitary tumors such as vascular endothelial growth factor (VEGF) and VEGF receptors, fibroblasts growth factors (FGF), transforming growth factor beta (TGFB), interleukins, interferons, and matrix metalloproteinases (MMPs) and inhibitors of MMPs have been examined in animal and human pituitary tumor models. However, many other significant regulators of angiogenesis including angiopoietins, angiostatin, and thrombospondins have not been studied extensively in pituitary tumors to date. Newer concepts and developments in angiogenesis such as vasculogenic mimicry and gene therapy approaches to angiogenesis in cancer treatment are also discussed.

Targeting the tumor blood vessel network to enhance the efficacy of radiation therapy

It has been well established that the vascularization of solid tumors is a prerequisite if a clinically relevant size is to be reached. For progressive tumor growth, the vessel network must continuously expand to satisfy the neoplastic cells' nutritional needs and waste product removal requirements. This utter reliance of the tumor on its vasculature provides a logical target for new approaches to cancer therapy. Indeed, there currently exists a great deal of enthusiasm for the development of interventions that compromise the growth and/or function of the tumor neovasculature. Two primary directions are being pursued. Inhibitors of angiogenesis seek to interrupt the angiogenic process to prevent new vessel formation. Antivascular approaches aim to cause direct damage to the tumor endothelium and thus lead to extensive secondary neoplastic cell death. The application of such strategies as adjuvants to conventional radiation treatments offers unique opportunities to develop more effective cancer therapies.

Prognostic significance of tumor-induced angiogenesis in colorectal cancer

Introduction Tumor-induced angiogenesis is a central pathogenic step in the process of tumor growth, invasion and metastasis. The aim of this study was to analyze the quantitative expression of angiogenesis in colorectal carcinoma and to determine if and how angiogenesis correlates with other clinicopathologic factors and prognosis. Material and methods This study included 40 patients who underwent curative resection of colorectal cancer at the Department of Surgery of the Senta General Hospital with complete 5 years follow-up or till death. Microvessels were identified immunohistochemically using monoclonal CD31 antibodies. The microvessel count was assessed by means of stereology with test grid M42, as well as vascular surface density in the stromal volume at the invasive front of colorectal cancer. Results Tumor-induced angiogenesis count of colorectal carcinomas statistically significantly correlated with stage of disease and histologic tumor grade There was no significant correlation between intratumoral microvessel density and sex and age of patients, localization and histologic tumor type Five-year survival rate in patients with hypervascular colorectal tumors was statistically significantly lower than in patients with hypovascular tumors Thus, microvessel density in colorectal cancer is an independent prognostic factor, but its significance is less than the importance concerning stage of disease and histologic grade of tumor. Conclusions Intratumoral microvessel density quantification in histologic specimens of colorectal carcinoma reflects the biological malignant potential of tumors and may be a useful additional predictive marker. Assessment of intratumoral microvessel count might be used for determining the pathologic stage when adjuvant therapy is concerned. Microvessel density in tumor specimens is valuable in stratifying patients in planning appropriate adjuvant and antiangiogenic therapy after surgery.

Angiogenesis in patients with craniopharyngiomas: correlation with treatment and outcome

BACKGROUND

Craniopharyngiomas are histologically benign epithelial neoplasms of the sellar region that often exhibit aggressive and invasive growth. The authors hypothesized that tumor proliferation, spread, and recurrence are angiogenesis dependent and investigated the significance of vascularization relative to biologic behavior. To the authors' knowledge, angiogenesis for patients with craniopharyngiomas has not been examined to date.

METHODS

The authors measured microvessel densities in resected, histologically proven craniopharyngiomas using immunostains for CD-34, a monoclonal antibody that selectively recognizes endothelial cells. Both histologic types of craniopharyngiomas, adamantinomatous and papillary, were included in the study. In addition, the cellular distribution of vascular endothelial growth factor (VEGF), a strong stimulator of new vessel formation, was assessed by both immunohistochemistry and in situ hybridization for VEGF receptor 2 (VEGFR-2) mRNA expression.

RESULTS

Histologically, small numbers of capillaries were identified in temporal stroma but not in their epithelial components. Immunohistochemistry revealed strong, conclusive cytoplasmic immunoreactivity for VEGF in the epithelial cells of both adamantinomatous craniopharyngiomas and papillary craniopharyngiomas. In situ hybridization showed that VEGFR-2 mRNA was expressed widely, not only in neoplastic epithelium but also in capillary endothelium.

CONCLUSIONS

Tumors with greater microvessel density regrow more frequently compared with tumors that have lower microvessel density, suggesting that the extent of angiogenesis is of prognostic value in patients with craniopharyngioma. VEGFR-2 may act as a key modulator of VEGF activity in endothelial cells and nonendothelial cells, indicating that VEGF plays an important role in the behavior of craniopharyngiomas.

Relevance of biologic markers in colorectal carcinoma: a comparative study of a broad panel

BACKGROUND

Although pathologic stage is currently the main prognostic indicator for patients with colorectal carcinoma (CRC), mounting evidence suggests that, in its current form, it is insufficient to predict clinical outcome. To assess biologic markers of primary CRC that may improve clinical staging and provide useful information for the application of novel therapeutic strategies, the authors investigated a panel of markers that included transforming growth factor alpha (TGF alpha), epithelial growth factor receptor (EGF-R; the protein product of the c-erb B2/HER-2 oncogene), matrix metalloproteinase 2 (MMP-2), insulin-like growth factor II (IGF-II), vascular endothelial growth factor (VEGF), and angiogenesis, as evaluated by microvessel density (MVD).

METHODS

Two groups of CRC were studied: 1) surgical samples from patients who achieved a disease free survival of at least 6 years (CRC-M0) and 2) surgical specimens of both primary tumors and synchronous or metachronous liver metastases (CRC-M1).

RESULTS

Chi-square analysis revealed that expression levels of TGF-alpha, c-erb B2/HER-2, MMP-2, IGF-II, VEGF, and MVD (but not EGF-R) were significantly higher in CRC-M1 samples compared with CRC-M0 samples (P < 0.001, P < 0.05, P < 0.001, P < 0.001, P < 0.01, and P < 0.001, respectively). Logistic regression analysis showed that TGF-alpha, IGF-II, and MMP-2 had significantly greater expression in CRC-M1 samples independent of the other variables (including tumor classification, histologic grade, and patient age). If all three markers had > or = 25% expression, then the probability of developing liver metastasis was 99.5%.

CONCLUSIONS

Based on the evidence of this study, TGF-alpha MMP-2, and IGF-II seem suitable candidates for a selective panel of markers designed to provide significant additional information with respect to the current pathologic staging system for patients with colorectal carcinoma.

Angiogenesis in advanced colorectal adenocarcinoma with special reference to tumoral invasion

BACKGROUND

Angiogenesis is a crucial step in tumor growth and progression. Its quantification by microvessel counting has a prognostic value in several types of malignancies and recently has been appraised in gastrointestinal tumors.

AIM

To assess the prognostic significance of microvessel quantification in colorectal carcinomas, studying its association with hematogenous metastases, survival and clinicopathological variables such as size, histologic differentiation and depth of tumoral invasion.

PATIENTS/METHODS

Forty eight patients with colorectal adenocarcinoma were included in this study. Histologic sections of invasion tumoral margin (4 microns) were analyzed and endothelined microvessels were immunostained with monoclonal mouse Von Willebrand Factor (anti-FVIII). The microvessel count was performed from the identification of the area with increased microvessel density--hot spots--and results of the mean in five of these fields.

RESULTS

The cut-off microvessel count was 14 microvessels/0.785 mm2, which divided the sample into hypovascular and hypervascular groups. While 2/8 (25%) tumors with muscularis propria invasion were classified as hypervascular, 11/15 (73%) tumors with serosa or perivisceral fat were classified as hypervascular. However, a non-significant statistical association was found between the angiogenesis quantification, hematogenous metastases, survival and clinicopathological variables such as size and histologic differentiation of the tumor.

CONCLUSIONS

The findings of significantly increase of microvessel count in conformity with tumoral invasion depth supports the hypothesis that tumor progression might be related to angiogenesis. Although angiogenesis is an important step in the tumoral growth and during the metastatization process, other factors can be implicated.

Morphologic analysis of microvessels in colorectal tumors with respect to the formation of liver metastases

BACKGROUND AND OBJECTIVES

Overexpression of VEGF and proliferation of microvessels are strongly related to liver metastases, however, morphologic analyses of microvessels in liver metastases have not been reported. The purpose of the present study was to examine the correlation between liver metastases and the diameters of microvessel lumens in the tumor tissue.

METHODS

Fifty-nine patients with liver metastases from colorectal cancers and 112 patients who underwent curative colorectal resection and survived without any recurrence were reviewed. Microvessel density (MVD) and the diameters of the lumens of individual microvessels were assessed.

RESULTS

There was a significant difference in terms of the mean MVD of primary tumors between patients with liver metastases and those without liver metastases. The numbers of patients with liver metastases who had microvessels 100-200 microm in diameter and microvessels more than 200 microm in diameter were significantly greater than patients without liver metastases. Microvessels with lumens more than 100 microm in diameter were not detected in the liver metastatic lesion.

CONCLUSION

Large microvessels in the primary tumor favor intravasation of cancer cells.

Targeting tumor blood vessels: an adjuvant strategy for radiation therapy

BACKGROUND AND PURPOSE

The neovascularization of tumor cells is a prerequisite if a clinically relevant tumor size is to be reached. A continuously expanding vessel network supplying nutritional requirements and removing waste products is essential for continued tumor development, growth and survival.

RESULTS

In many tumors, the growing endothelium is unable to fully support the demands of the neoplastic cell population. As a consequence of the inadequacies of the resulting aberrant vasculature, microenvironmental conditions develop in tumors which are not only detrimental to the response of tumors to conventional anticancer treatments, but may lead to or predispose cells to genetic modifications resulting in more aggressive phenotypes and higher metastatic potential. Yet the utter dependence of the tumor on its induced vessel formation for growth, survival and spread has also created a great deal of enthusiasm for developing therapeutic approaches to specifically targeting the tumor microcirculation.

CONCLUSIONS

The application of such strategies as adjuvants to conventional radiation treatments offers unique opportunities to develop more effective cancer therapies.