Aneuploidy has been long associated with genetic instability and tumorigenesis. Dewhurst and colleagues examined the evolution and consequences of chromosomal aberrations in long-term culture of a diploid colon cancer progenitor cell line over time. Rare cells that survive genome doubling, tetraploids, have a greater tolerance for further chromosomal abnormalities. Furthermore, tetraploidy was found to be associated with a low probability of disease-free survival.