The treatment of cancer is based today, in many cases, to molecules that inhibit the growth of the primary tumor. Both with conventional chemotherapy agents as well as with recent target-based treatments is thus usually achieved a control of the tumor growth. The last two years, however, the literature published reports on therapeutic molecules employed indeed inhibit the growth of the primary tumor, but an unexpected turn pro-metastatic effect to have. The aim of this project is to correlate the effect of linear bestralingsgradiënten different mouse structures with metastaseringsefficiëntie. This research should enable you to identify radiation doses which increase metastaseringsefficiëntie in order to avoid this in clinical practice.