[Current concepts of metastasis classification]

New findings of molecular pathology provide better insight in the process of metastasis. Single findings in few patients are, however, useful in being taken as parameters which signalize the individual risk of a metastasis not detectable by clinical methods. In addition they cannot be used as prognostic factors. On the other hand, there are important data which indicate a prognostic significance of so called isolated tumour cells, which can be detected by cytological or molecular methods. Current and proposed classifications of metastasis reflect the necessity, to better describe the situation of an individual patient to design an optimal therapy. Such more exact classifications will form the basis of a more differentiated therapy and will give more exact data to estimate prognosis.