More than half the patients with malignat tumours have at the time of diagnosis already remote metastases or they develop remote dissemination after different intervals following termination of local treatment. Organ complications in case of metastatic dissemination are for the majority of patients the most life threatening condition. In therapeutic decisions the approach to some solid tumours is the same as in systemic diseases. The possibility to achieve a long-term therapeutic effect during conventional systemic therapy are limited in metastatizing solid tumours of adult age. Assessment of the extent of the disease incl. detection of metastatic dissemination is of decisive importance for the selection of therapeutic strategy. Imaging methods such as computed tomography, ultrasonography and nuclear magnetic resonance provide basic structural anatomic information.The limitating factor is obtaining functional information on tumor tissues and the possibility to differentiate the residual disease from non-viable or necrotic tumor masses. These data can be provided by radiopharmacological imaging methods such as positron emission tomography. Introduction of new imaging methods is becoming increasingly important when new therapeutic methods are used where the effect of the therapeutic result does not mean necessarily reduction of the tumour volume. Research of the metastatic process involved revolutionary changese lucidating individual stages linked in a cascade pattern. The metastatic potential of human tumours correlates with the expression of a number of genes regulating tumour growth (EGF - epidermal growth factor, IGF - insulin like growth factor) motility of tumour cells (AMF - autocrine motility factor) the process of angiogenesis (VEGF - vascular endothelial growth factor, bFGF - basal fibroblastic growth factor, interleukin-8) and the invasiveness (genes for the matrix of metalloproteinase MMP-2/MMP-9). Expression of the surface glycoporotein E-cadherin which influences the cohesiveness of cells is in an inverse relationship with the invasiveness and metastatic potential. Identification of the appropriate genes in a heterogeneous tumour population calls for multiparametric, multivariation analysis of gene expression. Understanding of this complex problem opened new possibilities of therapeutic action and improved curability of neoplastic diseases in all stages of the disease. Gradual more detailed understanding of individual stages of a multigrade process of metastatizing helped to reveal new potential target structures for treatment. In the process of angiogenesis these are metalloproteinases, angiogenic growth factors, endothelial cells and vascular structures of tumours. Practical use for therapeutic purposes will develop on the basis of results of clinical studies which are underway.

        Key words: Metastatizing of tumours - Imaging methods - Tumour growth regulating genes