Rare breast cancer link is tied to European-Jewish ancestry Discovery said to promise community screening test

September 29, 1995|By LOS ANGELES TIMES

DALLAS — A rare genetic defect linked to breast and ovarian cancer is eight times more common among Jewish women of European ancestry, researchers announced yesterday, 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, the mutation may account for up to 16 percent of breast cancers and 39 percent of ovarian cancer 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.

About 3 percent of the population of North America -- about 6 million people -- are Jewish. Almost all are Ashkenazi.

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, a noted authority on the genetics of breast cancer at the University of Washington.

"We are there now," she said. "We're stuck."

Many women have at least one or more risk factors for breast cancer. Up to 10 percent of the women diagnosed every year with breast cancer -- about 183,400 people in the United States -- have a family history of the disease.

nTC In the study, published yesterday in the journal Nature Genetics, a team from the Center for Genome Research, the National Cancer Institute and the University of California, San Diego, found that a distinctive variation of the cancer gene was so common among Ashkenazi Jews and so rare among the general population that it could easily serve to flag those Jewish women at higher risk of the diseases.

They carried out genetic tests on anonymous blood samples from 858 Ashkenazi Jews in the United States and Israel. They also tested blood from 815 people who were not chosen for their ethnic origin.

The unusual mutation turned up at a rate of 1 in 100 among the Jewish test group, compared with 1 in 800 among the general population.

That rate is at least three times higher than the rate for all the other known variations of the gene combined, and well within the range of many genetic diseases for which limited, routine screening is conducted.

National Cancer Institute scientist Jeff Struewing, who led the research group, said the scientists are not sure exactly how much this variation of the gene increases a woman's risk of developing breast or ovarian cancer.

Researchers estimated that a genetic screening test for the mutation could be available in a year, cost less than $40 and be so simple it could be easily automated.

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