British scientists have identified a faulty gene linked to over half of all breast cancer cases, in what they claim is a major breakthrough in fighting the killer disease.
The gene is also linked to half of bowel and prostate cancers and one in four ovarian and bladder cancers, said the experts from Cambridge University's pathology department.
The NRG1 gene is found on chromosome 8, one of the packages of DNA inside cells. Cancerous cells are missing the section of chromosome 8 which carries the NRG1 gene, experts have discovered.
"I believe NRG1 could be the most important tumour suppresser gene discovery in the last 20 years as it gives us vital information about a new mechanism that causes breast cancer," said Doctor Paul Edwards.
"We found the gene on chromosome 8 partly by good luck and partly by good judgment. In every case that we looked at where a big chunk of chromosome 8 had been lost, at least part of the gene was lost.
"The gene was effectively 'turned off' in a lot of breast cancers," he added.
The gene is present in everyone's DNA, but becomes damaged in some people, allowing cancer to develop. Experts do not yet know exactly why the gene is damaged in some people and not in others.
"We have got strong evidence that the gene is implicated in breast cancer but we have no reason to think it's not the same for other cancers, including prostate and colon cancer," said Edwards.
"Finding out what genes have been turned off in these cancers is an enormous help in understanding what has gone wrong with their biology."
The study was published in the journal Oncogene and funded by Cancer Research UK and Breast Cancer Campaign -- whose head of research Arlene Wilkie also trumpeted the significance of the discovery.
"Knowing the identity of this gene will lead to far more detailed studies of how it works and how it is involved in breast cancer development," she said.
"This research is a major step forward in understanding the genetics of cancer and could open up a host of new strategies to improve diagnosis and treatment.
More than 45,000 women are diagnosed with breast cancer every year in Britain, of whom some 12,000 people die, according to Cancer Research figures.