Despite significant advance, cancer treatment remains suboptimal. Anatomical and physiological differences between humans and simple model organisms like Drosophila are many and major, and preclude the modelling of key aspects of the disease as it proceeds in vertebrates. However, malignant tumors in vertebrates and flies are made of cells that have derailed from their normal course of development, grow out of control, become immortal, invasive, and kill the host. Moreover, like most solid human tumors, Drosophila malignant tumors display chromosomal instability and copy number variation. In addition, some of them are characterized by the upregulation of germline genes, a distinct feature of certain human cancers. Drosophila tumor models offer an unprecedented opportunity to study these basic malignant traits, which characterize human tumors, in a genetically tractable organism, applying sophisticated genome-wide and comprehensive functional assays at a rate and with a level of detail that are not possible in vertebrates. The goal of this project is twofold: (1) to identify new paths of intervention to inhibit tumor growth, and (2) to determine the origin and function of aneuploidy and changes in gene copy number in malignant growth. We are expectant that the results obtained during the course of this project might eventually have a real impact in human health.