Researchers in three separate studies have found six new variation sites in the human genome project that might increase the risk of developing breast cancer, the New York Times reports. According to the researchers, the six new discoveries when combined with genes already known to increase breast cancer risk might account for a large fraction of the overall genetic risk of the disease, the Times reports.

In a study published in the May 27 issue of the journal Nature, Douglas Easton of the Genetic Epidemiology Unit at the University of Cambridge and colleagues found five new sites where a common variation confers an increased risk of breast cancer (Wade, New York Times, 5/29). For the study, Easton and colleagues looked at the DNA of 21,860 people who had been diagnosed with breast cancer and 22,578 who had not. The researchers found mutations in four genes -- FGFR2, LSP1, MAP3K1 and TNRC9 -- that were more common in the people who had breast cancer, Reuters Health reports.

A second study was published online in the journal Nature Genetics and conducted among more than 2,200 women of European ancestry. A team led by David Hunter of the Harvard School of Public Health found four mutations in FGFR2 that are associated with breast cancer in women who have experienced menopause and who do not have known relatives with breast cancer. According to Reuters Health, women who carry one copy of FGFR2 have a 20% increased risk of developing breast cancer and women who carry two copies have a 60% increased risk. About 60% of the women in the Harvard study carried at least one copy of FGFR2, Reuters Health reports (Fox, Reuters Health, 5/28).

In a third study, also published online in Nature Genetics, a team of researchers led by Simon Stacy from Decode Genetics found that 25% of women of European descent carry one copy of a DNA variant associated with breast cancer, conferring a 44% increased risk of developing the disease compared with women who do not have the variant. In addition, the study found that 7% of women have two copies of the variants and a 64% increased risk of developing breast cancer.

According to the Times, the variation sites found in the three studies do not have a biological function and are believed to be associated with breast cancer based on statistics rather than on evidence. In addition, the findings are not understood well enough to diagnose breast cancer or to develop new treatments. However, researchers say the findings are critical for understanding the biology of breast cancer and developing future treatments (New York Times, 5/28).

• The Treating Physician as Researcher
• Medical Case Studies
• Medical Studies FAQ

• Medical Studies - Medline Plus
Provides information on the latest in medical research through various resources