A rare genetic defect linked to breast and ovarian cancer is eight times more common among Jewish women of European ancestry, researchers announced Thursday, promising the first inexpensive community screening test for the most common cancer among American women.
Researchers at the National Institutes of Health offered the first direct evidence that an easily detectable alteration in a known breast cancer gene is present not only in high-risk families but also in a specific ethnic group among the general population.
They estimate, for example, that the mutation may account for up to 16% of breast cancers and 39% of ovarian cancers in Jewish women of European, or Ashkenazi, descent under age 50.
Francis Collins, director of the NIH National Center for Genome Research, said the newest finding about how heredity affects breast cancer represents "a sea change in how people think about genetics and public health" because it offers the possibility that large numbers of people can be screened for cancer.
About 3% of the population of North America--about 6 million people--are Jewish. Almost all belong to Ashkenazi families.
*
Against the promise of an affordable diagnostic test, however, scientists say they must weigh the risk that a genetic test designed for a specific ethnic group may be used as a tool of discrimination to deny insurance or employment to people often already singled out by prejudice.
Authorities also question the value of a genetic diagnosis when effective medical treatment options for the disease remain so limited. No new fundamental treatment for breast cancer has been introduced in 20 years, experts said, and survival rates have improved only marginally.
"There was bound to be a stage when we could identify people at risk [for breast cancer] and not be able to do anything about it," said Mary-Claire King of the University of Washington, who is a noted authority on the genetics of breast cancer.
"We are there now," she said. "We're stuck."
Many women have one or more risk factors for breast cancer. Up to 10% of the women in whom breast cancer is diagnosed--about 183,400 a year in the United States--have a family history of the disease.
When scientists last year discovered a single breast cancer gene, called BRCA1, it raised hopes for a simple test that could be used for all women with a personal or family history of breast cancer. The gene is believed to account for about half of all inherited breast cancers and an equally large number of ovarian cancer cases.
