Scientists have proposed a radical new theory that cancer may be caused by a set of genes that have been passed on from our early ancestors and are "switched on" in the initial stages of an organism's life as cells differentiate into specialist forms.
The genes that are involved in the early development of the embryo and that are silenced, or switched off, thereafter become inappropriately reactivated in the adult as a result of some sort of trigger or damage, such as chemicals, radiation or inflammation, researchers suggest.
Orthodox explanations suppose that cancer results from an accumulation of random genetic mutations, with the cancer starting from scratch each time it manifests.
In the journal Physics World, Paul Davies, principal investigator at Arizona State University's Center for Convergence of Physical Sciences and Cancer Biology, explains the new theory.
The theory, drawn together with Charles Lineweaver of the Australian National University, suggests that cancer is a throwback to an ancient genetic "sub-routine" where the mechanisms that usually instruct cells when to multiply and die malfunctions, thus forcing the cells to revert back to a default option that was programmed into their ancestors long ago.
"To use a computer analogy, cancer is like Windows defaulting to 'safe mode' after suffering an insult of some sort," Davies said.
The result of this malfunction is the start of a cascade of events that we identify as cancer - a runaway proliferation of cells that form a tumour, which eventually becomes mobile itself, spreading to other parts of the body and invading and colonising.
"Very roughly, the earlier the embryonic stage, the more basic and ancient will be the genes guiding development, and the more carefully conserved and widely distributed they will be among species," Davies said.
Several research teams around the world are currently providing experimental evidence that shows the similarities between the expression of genes in a tumour and an embryo, adding weight to Davies and Lineweaver's theory.
