and that predisposition epigenetic -- damage to DNA . The possibility is always there , what differs is the gene regulation , switches that can be either turned on or off .
What in the internal , chemical , environment is conducive to altered cells that are tumour and cancer forming.
"Epigenetic dysregulation is central to cancer development and progression. This dysregulation includes hypomethylation leading to oncogene activation and chromosomal instability, hypermethylation and tumor suppressor gene silencing, and chromatin modification acting directly, and cooperatively with methylation changes, to modify gene expression. In addition, disrupted genomic imprinting appears to contribute to colorectal cancer risk, and serves as a gatekeeper in Wilms tumor. A cancer predisposing disorder, Beckwith-Wiedemann syndrome, usually arises from epigenetic errors, solidifying the causal role of epigenetics in cancer. While cancer epigenetics has been reviewed extensively elsewhere, the main focus of this review will be to present the view that epigenetics and genetics are complementary in the area of cancer etiology, the focus of this volume. I propose a hypothesis in which epigenetic alterations contribute to tumor progression, but they also increase the probability that genetic changes, when they occur, will lead to cancer initiation. This hypothesis could contribute to a new understanding of the role of environmental carcinogens that may not be fully explained through a purely genetic view or by tests, such as bacterial mutation frequency, that ignore epigenetic factors.:
"While many cancers have been linked to mutations in the DNA sequence of particular genes, epigenetic changes do not involve genetic mutations. Instead, epigenetics allows two cells with identical DNA sequences to behave in wholly different ways. Epigenetic proteins effectively edit the genome by turning off genes that are not needed. This editing process
is what allows human beings to have specialized cells — like nerve cells, bone cells and blood cells — that look and behave differently, even though they share the same DNA."