Scientists have made a massive leap towards identifying the roots of hereditary breast cancer after a groundbreaking study picked up new genes which can increase the risk of the disease.
Until now, it was not known which genes cause 75 per cent of inherited breast cancer, which affects thousands of British women every year.
Professor Douglas Easton
But the Cambridge-based study, published online in the Nature journal, found four genes that can increase a woman's chances of developing the disease. They have never previously been linked to inherited breast cancer and are responsible for another 4 per cent of inherited cases, equating to between 88 and 176 women a year.
Scientists believe the discovery is the first step towards finding many more breast cancer genes, and the same research method is already being applied to several other cancers.
Professor Douglas Easton, director of Cancer Research UK's genetic epidemiology unit in Cambridge, said: "We are very excited by these results because the regions we identified don't contain previously known inherited cancer genes.
"This opens the door to new research directions."
He continued: "Now we know these search methods are effective, we think that many more breast cancer genes can be found.
"These methods are already being applied by Cancer Research UK to find genes for a whole range of other cancers, including prostate, bowel and lung cancer."
The DNA of almost 50,000 women was studied by an international research team led by scientists in Cambridge in the world's first large-scale "whole genome search".
Around half of the women in the study were breast cancer victims and the other half were healthy women from the general population. Researchers found five regions of DNA that were present more often in the cancer sufferers, leading them to four genes they believe are responsible for the higher cancer risk.