Angiogenesis in superficial transitional cell carcinoma of the human urinary bladder
Aims: To determine whether microvessel density (MVD) could be measured in papillary superficial transitional cell carcinoma of the human urinary bladder in a simple, meaningful and reproducible way. Also, to determine whether angiogenesis, as measured by MVD, at presentation is related to subsequent recurrence or progression of superficial bladder cancer and its relationship to known angiogenic cytokines. Methods: Immunohistochemical techniques were used to measure MVD (using CD34), vascular endothelial growth factor (VEGF) thrombospondin-1 (TSP-1) (using both TSP Ab-4 and TSP Ab-7 antibodies), thymidine phosphorylase (TP) and p53 in 5?m sections of formalin-fixed, paraffin-embedded samples of primary superficial bladder cancer. A computer image analysis system was devised to measure MVD and compared to a standard manual technique. The percentage expression of VEGF, TSP-1, TP and p53 was recorded. MVD and the cytokines were correlated with outcome using binary logistic regression analysis. Results: The database included 293 cases of primary superficial bladder cancer. The computer image analysis system was able to measure MVD in superficial bladder cancer and correlated strongly with manual counting (r=0.95). In a multivariable analysis, MVD (p<0.0001), TSP (Ab-7) tumour staining (p=0.001), decreased TSP (Ab-4) perivascular staining (p=0.007), tumour stage (p<0.0001), multiplicity (p=0.01), age (p=0.003) and aspirin consumption (p=0.004), were all independent predictive factors for superficial bladder cancer progression. MVD in this study showed a positive correlation with p53 and the pro-angiogenic factor TP. Low perivascular TSP staining correlated with increased MVD. Conclusion: This study has shown that MVD can be measured in superficial bladder cancer. A method has been described that is accurate, reproducible and time efficient.