The problematic nature of metastasized renal cell carcinoma.

The treatment of metastatic renal cell carcinoma presents major unsolved problems. All of the therapeutic options have shown only minimal success rates. In addition to partial clarification of tumour genesis, basic findings regarding the heterogeneity of tumors were made. Options for further therapeutic developments will result from increased knowledge of the pathogenesis of metastatic spread. After the growth of new tumor vessels (angiogenesis) the metastasizing cell must break away from the cell formation (loss of cadherines). By migration it reaches the vessel wall which is made permeable by proteolysis (matrix metaloproteinase). After reaching the target organ, adhesion results (adhesion molecules and integrins) within the vessel system and ex-travasation follows. With stimulation the metastatic cell will grow in the target organ. Growth is subject to the cytokine control mechanism (interleukines). Based on these individual steps, future therapeutic options can be developed. However, the treatment modalities at our disposal today must not be neglected: for example, immuno(chemo)therapy and various radiation therapies as well as metastases surgery.