A progression puzzle

Abstract

Most, if not all, human tumours develop through a succession of genetic and epigenetic changes that confer increasingly neoplastic (cancer-like) characteristics on cells. Indeed, this multistep process has been likened to darwinian evolution within the microcosm of living tissues, in which the units of selection are individual cells. A cell that possesses advantageous characteristics (ones that favour survival and proliferation) is selected to become the progenitor of a successor cell population that eventually dominates the tumour mass. A rare variant that arises among the many successor cells will, in turn, initiate the next round of clonal succession. Between six and ten such clonal successions may be required to generate highly malignant human cancer cells.