The human body is composed of different cell types and tissues and cancers can arise from any of these cells. Cancer, the last stage of tumour growth is driven by genetic and epigenetic alterations that allow cells to proliferate indefinitely and escape mechanisms that normally control their survival and migration and cellular defense barriers. Oncogenes and tumour suppressors are the class of the genes which are responsible for the initiation and progression of tumour. Cancer is of three types of Carcinoma, Sarcoma and Leukemia depending upon the cell of origin and caused by different cancer causing agents known as carcinogen. Cancer is a genetic disease, and a spectrum of DNA variations is responsible or associated with particular type of cancer. Many of these changes map to signalling pathways that control cell proliferation and death leading to distortions of wider signalling networks. These mutations cremoveng cellular proto-oncogenes to oncogenes can cause hyper activation of these signalling, whereas inactivation of tumour suppressor genes removes negative regulators of signalling pathways. These information at molecular level gives insight for the cancer therapy.
6) ability to invade tissue and establish secondary tumours [2].Cell proliferation is carefully balanced by cell division and cell death which gives the definite life span to a cell. This balance was disrupted in malignant transformation of the cell and a single faulty cell may give rise to the clone of identical cells expanding to a considerable size, producing a tumour. A tumour which is incapable of indefinite growth and does not invade the healthy surrounding tis-Am J Biomed Sci & Res