ABSTRACT
Almost the fi rst thing researchers noticed from the time they began looking at cancer cells under the microscope was that they had excess chromosomes. One of the pioneers was David Hansemann who observed asymmetric mitoses in all the epithelial cancers he examined (Hansemann 1890). He seems to have been the fi rst to connect cancer to an imbalance in the number of chromosomes. Hansemann captured the essence of cancer as, “a process carrying the cell in some entirely new direction-a direction, moreover, which is not the same in all tumors, nor even constant in the same tumor… . Th e anaplastic cell then is one in which, through some unknown agency, a progressive disorganization of the mitotic process occurs, which in turn results in the production of cells that are undiff erentiated in the sense that those functions last to be acquired, most highly specialized…are more or less lost; but rediff erentiated in the sense that the cancer cell is not at all
an embryonic cell, but is a new biologic entity, diff ering from any cell present at any time in normal ontogenesis. But…this entity displays no characters absolutely and completely lacking in the mother cell… . Its changed behavior depends on exaltation of some qualities, and depression of others, all at least potentially present in the mother cell.” (Translated by Whitman (Whitman 1919).) Hansemann’s “unknown agency” has turned out to be the relentless randomization of the genome caused by aneuploidy, the subject of this book.
