Cancer is a genetic disease; it develops from mutations within the genes of cells. The “oncogenes” and “tumor suppressor genes” present in all individuals play a significant role in tumor formation.
Oncogenes, activate cell division and influence embryonic development and tumor suppressor genes halt cell division. Since these two genes are typically found in normal human cells, certain mutations in them may transform their normal function resulting in the conversion of normal cells into tumor cells.
Either inherited defects or acquired mutation due to exposure to carcinogens may cause conversion of normal cell into a tumor cell. Current evidence indicates that carcinogenesis results from a complex interaction of carcinogens and accumulated mutations in several genes.