Molecular biology of dissemination in bladder cancer--laboratory findings and clinical significance.

Recent molecular biology investigations have demonstrated that tumor progression and dissemination in bladder cancer is a highly complicated phenomenon, consisting of multiple distinct steps and regulated by a great number of different genes. Some of these genes involved in the specific steps of tumor progression and dissemination have been identified. Several oncogenes, e.g., the epithelial growth factor receptor (EGF-R), and tumor-suppressor genes, e.g., the p53 gene, have been found to correlate significantly with tumor progression. The decreased expression of cell-adhesion molecules such as E-cadherin appears to facilitate tumor-cell detachment in the primary tumor, whereas expression of the intercellular adhesion molecule (ICAM)-1 might be of relevance for cell attachment at the metastatic site. Tumor invasion through the basement membrane has been correlated with a decreased expression of laminin and elevated urinary levels of acidic fibroblast growth factor. Although the complex processes related to dissemination are far from being completely understood, the finding of differential expression of distinct genes appears to provide the first targets for therapeutic intervention.