TORONTO.– Six or more cups of coffee a day may dramatically cut the risk of breast cancer by as much as 70 percent among women with one of the gene mutations linked to an very high risk of the disease, a new study shows.  

The reduced risk, however, only applied to caffeinated coffee and women who carry a mutation in either the BRCA-1 or BRCA-2 genes. The study was published in the Jan. 1, 2006 issue of the International Journal of Cancer.  

The research team led by Dr. André Nkondjock of the University of Montreal, and senior author Dr. Steven A. Narod of the University of Ohio found that, among women with either of the two breast cancer genes, the risk of actually developing breast cancer decreased in proportion to the volume of coffee consumed over time. The more the women drank, the lower the risk of breast cancer.  

"These results suggest that among women with BRCA gene mutations, coffee consumption is unlikely to be harmful," the researchers wrote. "And that high levels of consumption may in fact be related to reduced breast cancer risk."  

In the study the researchers administered questionnaires to 1,690 women, half of whom had at least one of the so called breast cancer genes and had been diagnosed with breast cancer, and half who had one of the gene mutations but did not have cancer. The women were asked to estimate their average daily coffee consumption, along with a number of other dietary and lifestyle issues.  

After adjusting for other factors, such as number of births, smoking, age, and oral contraceptives use, they found that those who drank four to five cups of coffee a day saw their risk fall by 25 percent, while the majority who drank one to three cups had a relative risk reduction of 10 percent compared with women who drank no coffee.  

The greatest risk reduction, by far, was among the 5 percent of the women who drank six or more cups a day, with an average risk reduction of 69 percent.  

The result poses an awkward dilemma for doctors with BRCA patients at risk for breast cancer. It is known that caffeine helps the body break down estrogen, the female hormone that can stimulate breast cancer.  

Coffee is also an important source of phytoestrogens, which may have protective effect against cancer. At the same time, caffeine can rob the bones of important minerals and hasten osteoporosis.  

Despite the new data, the researchers won't be recommending enormous quantities of coffee for women with the BRCA genes until larger studies can confirm this finding.