A strong family history, involving dominant genes, is already well established as a cause of breast cancer. Mutations in the so-called BRCA1 and 2 genes are estimated to account for about 15-20 per cent of familial breast cancer.
But the Cambridge research may lead to the development of further tests to identify women who are at risk from other genetic mutations. Professor Bruce Ponder, of the Cancer Research Campaign Department of Oncology at the university, said: "The number and type of genes that account for the remainder of familial breast cancer is not clear. It is, however, plausible, that at least some of this genetic predisposition is attributable to the effects of multiple, common, but individually weak genes".
Identifying such genes could help scientists to create "genotype profiles" to determine the risk of individual women at risk from the disease. These could be used in pre-symptomatic screening, diagnosis and treatment of the disease.
Professor Ponder believes that "genotype profiles" may ultimately prove to be more effective than "established clinical risk factors" in determining if an individual woman is at risk. These factors include age, reproductive factors including age of menarche (first period) and menopause, high-fat diet, alcohol consumption and high socio-economic status.
He explained: "These established risk factors are all very important, but they are not good discriminants of risk for the individual. It's been shown that if you take a series of ten thousand women and evaluate them according to these factors, you can predict fairly accurately how many of them will get breast cancer. But what you can't do is to tell which women will get it and which won't.
"We hope that the genetic profiles will be much more specific - and tell us which individuals are at high risk and which are not."
What is the next stage in the research? "This is a field which is at the very beginning. We now need our results to be replicated by two or three other groups."
Abstract no: 923.
Further information: Maria Maneiro
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