Researchers are confident that their findings will allow a screening programme, in which the inherited risk of developing cancer can be assessed for every patient, to be in place in an estimated 12 to 15 years. According to the report, four common genes were identified and a fifth is on the verge of being pinpointed by researchers investigating the causes of breast cancer, almost doubling the number of known rogue genes.
Commenting on the development, Harpal Kumar, chief executive of Cancer Research, UK, said this was "an outstanding discovery" that would "open doors across the globe". Independent cancer specialists welcomed the research. Professor Karol Sikora, of the Imperial College School of Medicine in London, said: "This set of incredible papers points to the future."
According to a report in The Guardian, it is the most significant discovery in the field since the 1990s, when scientists identified two rare genes, BRCA1 and BRCA2, which make carriers likely to develop breast cancer. Breast cancer is twice as common in those who have a close relative who develops it due to a fault in a gene, although the presence of a faulty gene does not mean that cancer will definitely occur.
The scientists trawled large parts of the genome in 800 people. They identified 11,000 "tags", or blocks of DNA which point to genes, which were more common in women with breast cancer and studied them in 8,000
In the final process, which involved 40,000 women, they narrowed the search down to five tags which were significantly more common among women with breast cancer than those without. The tags pointed them to four genes which they believe are responsible for the increased breast cancer risk among the patients studied. Scientists expect that they will find a fifth.
One of the new genes, when found in a mutated form, increases the risk of developing the cancer by up to 60 per cent - giving a woman a one in six chance of the disease. Its most damaging variant is carried by one in six women, making it much more common than previously identified genes that contribute to breast cancer.
The success of a new "trawling technique" to assess 200,000 blocks of DNA simultaneously instead of one by one is expected to transform the search for treatments for all common cancers. While the research concentrated on identifying genes linked to breast cancer, the same technique can be used for other types of the disease and work has already started on applying it to prostate, bowel and lung cancer.
Professor Bruce Ponder of the University of Cambridge, who led the study, said the technique should speed up the rate of gene identification enormously for a range of cancers. The research was an international collaboration involving scientists from across Britain and the world and is published in several papers in the journals Nature and Nature Genetics.
