Genetic Instability of Tumors

One of two levels of genetic instability correlates with the vast majority of cancers. In most cancers genetic instability is observed at the chromosome level, resulting in losses 

Four major types of genetic alterations that affect growth-controlling genes have been identified in neoplastic cells and are the basis of human cancers. 

Translocation can also cause gains or losses of chromosomal material and generate new gene products. Simple translocations are characterized by distinctive rearrangements of chromosomal segments in specific neoplastic diseases, including leukemias and lymphomas. These specific translocations are necessary for the development and progression of the neoplasms in which they occur. 

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The three main treatment modalities currently available to cancer patients are surgery, radiotherapy, and chemotherapy [1], Radiotherapy and chemotherapy non-selectively inhibit rapidly proliferating cells, including cancer cells, and the generality of the antiproliferative effect of these treatments leads to the severe dose-limiting toxicides experienced by cancer patients. In addition, the genetic instability of tumor cells facilitates the development of resistance to radiotherapy and cytotoxic chemotherapy that eventually causes these treatment approaches to fail in most patients with solid or metastatic tumors. 

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