Genetic Changes in Tumor Cells

The mutations can lead to changes in the alignment of genes with products involved in signal transduction pathways and in growth regulation. It is assumed that these mutations are particularly important in the early phase of tumor formation. 

In the later phases of tumor formation, an increasing genetic instability occurs which is observed at the level of the chromosomes, particularly in the form of a change in the normal chromosome number (review Lengauer et al., 1998). 

Changes in the chromosome structure are often observed in tumors of the blood-forming system, the leukemias and lymphomas. They are almost always foimd in the later phases of aggressive solid tumors. These extensive reorganizations have wide-reaching consequences for growth behavior and functional performance. 

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