ABSTRACT
Cancer can be described as a process that leads to the abnormal spatial and temporal growth of cells and tissues within an organism. Cancers are almost always clonal in origin and result from the accumulation of genetic and epigenetic changes within a single somatic cell. As a result of these changes, cancer cells and their progeny fail to respond to normal growth regulatory signals from their environment, do not respect the normal physical boundaries and temporal limits spelled out by their normal developmental program, and acquire a selective growth advantage over their neighbors. It is therefore not surprising that cancer-specific mutations and epigenetic changes occur in genes that function in regulating normal cellular and organismal processes such as development, tissue homeostasis and repair, as well as cell growth and turnover.
