[Biological basis of metastasis formation]

Disseminated metastases are the most common cause of death in patients suffering from malignant disease. Tumor cell invasion and metastatic spread have often been considered to indicate an "undifferentiated" state of the tumor cells. In recent years, however, numerous studies point out, that invasiveness and the metastatic cascade are complex, highly differentiated processes based on manyfold interactions of the tumor cells and the surrounding stroma tissue. Changes of the cytoskeleton, adhesion molecules, motility, matrix-degrading enzyme activities, intercellular communication and intracellular signal transduction are considered to regulate the metastatic process. Thus basic research provides insight in pathogenetic mechanisms, which might represent targets for antimetastatic therapy in the future. This would be particularly mandatory in the case of malignant melanoma of the skin, where conventional cytotoxic chemotherapy has been rather disappointing.