Cancer: determinants and progression.

Cancer is the combination of uncontrolled cellular proliferation and immortality. It is a multi-step disease with a multi-factorial etiology. The determinants of cancer are many and varied including genetic predisposition, environmental influences, infectious agents, nutritional factors, hormonal and reproductive factors, radiation etc. However, the extent of the genetic involvement and their interaction with environment in tumorigenesis is still elusive. The six essential alterations in cell are proposed which determines the transition from normal cell to malignant. It includes--self-sufficiency in growth signals, insensitivity to growth-inhibitory (antigrowth) signals, evasion of programmed cell death (apoptosis), limitless replicative potential, sustained angiogenesis, and tissue invasion and metastasis. Nevertheless, the last two decades have seen rapid improvements in understanding the complex molecular mechanisms underlying tumorigenesis, yet the quest for unraveling the mystery is not over. Further study in this area is indispensable that could hold the promise of increasing our understanding of cancer etiology and possible preventive strategy.