Cancer cell genotypes are a manifestation of six essential alterations in cell physiology that collectively dictate malignant growth; self-sufficiency in growth signals, insensitivity to growth-inhibitory (anti-growth) signals, evasion of programmed cell death (apoptosis), limitless replicative potential, sustained angiogenesis and tissue invasion and metastasis. Environmental and endogenous DNA-damaging agents and genetic instability drive tumor progression by generating mutations in two types of genes, oncogenes and tumor suppressor genes, providing cancer cells with selective growth advantage and thereby leading to the clonal out growth of a tumor. In general, oncogenes (called proto-oncogenes in their normal, non-mutated form) promote cell proliferation and survival, whereas tumor suppressor genes inhibit cell growth. Cells proliferate only when required, as a result of delicate balance between growth [...]