New York, September 1, 1998-- A new genetic mutation has been found to modestly increase the risk of hereditary breast cancer in women of Ashkenazi Jewish descent but has an especially pronounced effect in those who already carry the other well-known BRCA mutations linked to the disease, report scientists at Memorial Sloan-Kettering Cancer Center and other research centers in the September issue of Nature Genetics. The findings indicate that the new mutation may serve as the first genetic modifier of breast cancer risk observed in women who are already susceptible to hereditary breast cancer.
"While we found the overall risk in inherited breast cancer linked to the APC mutation to be elevated, the increase was most significant in the women who had BRCA mutations," says Dr. Kenneth Offit, Chief of the Clinical Genetics Service at Memorial Sloan-Kettering and senior author of the study.
The study shows that the mutation called APC I1307K, increases the risk of inherited breast cancer by 50 percent in women of Ashkenazi Jewish descent, which translates to about a 15 percent lifetime breast cancer risk for this group of women with the APC mutation as compared to a breast cancer risk of about 10 percent for all women in the general population.
The current study estimate is based on blood samples drawn from a group of women of Ashkenazi Jewish descent with breast cancer who were compared to a control group of women of the same ethnic background without breast cancer. The study was conducted by investigators from Memorial Sloan-Kettering in collaboration with investigators from the University of Toronto in Ontario, McGill University in Montreal, Canada and other research centers.
In one group, 632 women with breast cancer were selected without regard to a
family history of the disease. The APC mutation was detected in 10.1 percent of
the women in this group. Of those who were found to have BRCA mutations, the
prevalence of the APC mutation was even
Contact: Kelli Stauning
Memorial Sloan-Kettering Cancer Center