Breast cancer: Scientists hail 'milestone' genetic find

Scientists say they now have a near-perfect picture of the genetic events that cause breast cancer.

The study, published in Nature, has been described as a "milestone" moment that could help unlock new ways of treating and preventing the disease.

The largest study of its kind unpicked practically all the errors that cause healthy breast tissue to go rogue.

Cancer Research UK said the findings were an important stepping-stone to new drugs for treating cancer.

To understand the causes of the disease, scientists have to understand what goes wrong in our DNA that makes healthy tissue turn cancerous.

The international team looked at all 3 billion letters of people's genetic code - their entire blueprint of life - in 560 breast cancers.

They uncovered 93 sets of instructions, or genes, that if mutated, can cause tumours. Some have been discovered before, but scientists expect this to be the definitive list, barring a few rare mutations.

'Important information'

Prof Sir Mike Stratton, the director of the Sanger Institute in Cambridge which led the study, said it was a "milestone" in cancer research.

He told the BBC: "There are about 20,000 genes in the human genome. It turns out, now we have this complete view of breast cancer - there are 93 of those [genes] that if mutated will convert a normal breast cell into a breast cancer cell. That is an important piece of information.

"We hand that list over to the universities, the pharmaceuticals, the biotech companies to start developing new drugs because those mutated genes and their proteins are targets for new therapeutics.

"There are now many drugs that have been developed over the last 15 years against such targets which we know work."

Image copyrightScience Photo Library

Image captionMutations in our DNA can cause cancer

Targeted drugs such as Herceptin are already being used by patients with specific mutations.

Prof Stratton expects new drugs will still take at least a decade to reach patients and warns: "Cancers are devious beasts and they work out ways of developing resistance to new therapeutics so overall I'm optimistic, but it's a tempered optimism."

There is also bad news in the data - 60% of the mutations driving cancer are found in just 10 genes.

At the other end of the spectrum, there are mutations so rare they are in just a tiny fraction of cancers meaning it is unlikely there will be any financial incentive to develop therapies.