BETHESDA, MD _ The race for the elusive breast cancersusceptibility gene, known as BRCA1, is nearing the finish line.Competition among the half dozen teams of scientists running thisinternational contest is so fierce that National Cancer Institute chiefSamuel Broder recently expressed dismay that the rivalry itself mayslow discovery.But one clear area of cooperation among these competitive scientists isin managing the media's and the public's expectations about whatlocating BRCA1 will really mean for women.Top breast cancer gene researchers gathered here at the NationalInstitutes of Health (NIH) on Tuesday to report on their progress at ameeting sponsored by the General Motors Cancer ResearchFoundation. They warned that the ability to conduct genetic tests hasoutpaced the ability of doctors to meaningfully interpret results forpatients and that public expectations of "a magical test" are unrealistic.Less Than 5 Percent Inherit Breast Cancer"In the clinic, we're finding that a large proportion of women don'trealize that hereditary mutations in BRCA1 apply to probably less than5 percent of breast cancer cases overall," Bruce Ponder, a Britishresearcher from Cambridge University said. "We're also seeing thatquite a number of people believe that if they test positive we have somesort of cure or prevention that we can offer, and of course it's not at allclear that we know what to do."According to a March of Dimes poll conducted in late 1992, 68 percentof Americans know "relatively little" or "almost nothing" about genetictesting. However, in the same survey, 72 percent said they would takegenetic tests to determine whether they or their children were at risk forserious disease.Likewise, 65 percent of survey respondents felt that genetic testingshould be offered to everyone, rather than limiting it to people whohave reason to believe they are genetically predisposed to a disease.At present, only women from large families with many members whohave breast and ovarian cancers can be tested for mutations in BRCA1.Even these individuals can only be tested in a research setting. Time-consuming genetic linkage analyses, which require DNA samples fromseveral affected relatives, is the only current method of identifyingBRCA1-mutation carriers."Once BRCA1 is found, a second tier of women may be helped _women who have just one or two cases of breast cancer in the family,such as a mother or a sister," said Mary-Claire King, a researcher fromthe University of California's Berkeley campus.But King said that this second tier of women won't be able to get a riskestimate for their particular BRCA1 mutation until information fromlarge numbers of families with the exact same mutation are catalogued.And she questioned whether the information alone, without some senseof the risk involved, was of any value to women.Fine-tuning Test Could Take Years"We'll also require a lot more information about the gene and all itsdifferent hot spots of mutation before we can tell women with anyaccuracy that they don't carry the gene," said King. She added thatdeveloping and fine-tuning a genetic test could take anywhere frommonths to years, depending on BRCA1's size (the larger the gene themore mutations there may be)."It's going to be quite some time before we can give useful informationto women in the population as a whole about their risk to breastcancer," said King. She warned that, in the wake of BRCA1'sdiscovery, commercial tests could become "widely available andminimally useful.""I'm not opposed to women having information no matter howdistressing, if it's meaningful," said King. "I am opposed to pushingtests that will cause a lot of emotional harm and provide noinformation."Francis Collins, director of the National Center for Human GenomeResearch, agreed with King and reiterated a theme he has beenstressing for months now: the era of genetic screening for cancer riskhas not yet arrived. Collins said genetic screening should be evaluatedin the same way new drugs are evaluated. It should be tested forefficacy and toxicity."The potential toxicities here are giving people misleading data, falsepositives or false negatives that could be devastating," said Collins. n

-- Lisa Piercey Washington Editor

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