BRCA Genetic Mutation Test Yields False Negatives For Breast Cancer Patients With Family History Of Breast, Ovarian Cancer, Study Says

Main Category: Breast Cancer
Article Date: 24 Mar 2006 - 9:00 PDT

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A commonly used genetic test to determine a person's risk of breast cancer failed to identify the BRCA1 and BRCA2 genetic mutations -- thought to increase risk of the disease -- in about 12% of people who have been diagnosed with breast cancer, who have a family history of breast or ovarian cancer and who previously tested negative for the mutation, according to a study published in the March 22 issue of the Journal of the American Medical Association, the New York Times reports (Pollack, New York Times, 3/22). About one in 400 people are believed to carry either the BRCA1 or BRCA2 mutation, both of which are believed to increase the chance of developing breast and ovarian cancers (Kaiser Daily Women's Health Policy Report, 2/16). The only commercially available BRCA test in the U.S. is made by Salt Lake City-based Myriad Genetics at a cost of about $3,000 (Burton, Wall Street Journal, 3/22). According to the Times, Myriad Genetics "has long been the focus of controversy because its patents give it a monopoly on the test" and some critics believe the "monopoly has slowed development of better testing" (New York Times, 3/22). Thomas Walsh of the University of Washington's departments of Medicine and Genome Sciences and colleagues examined 297 women and three men who had tested negative for the BRCA mutations, been diagnosed with breast cancer at some point in their lives and were members of families that have had at least four individuals with breast or ovarian cancer (Walsh et al., Journal of the American Medical Association, 3/22). Researchers tested the patients using various techniques including one known as MLPA, which is not commercially available in the U.S., the Milwaukee Journal Sentinel reports. The study finds that 52 of the participants had some type of genetic mutation, including 35 -- or about 12% -- who had the BRCA1 or BRCA2 genetic mutation (Newson, Milwaukee Journal Sentinel, 3/21). The MLPA test was developed by Amsterdam, Netherlands-based Microbiology Research Center-Holland (Dentch, Bloomberg, 3/21).

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Genetic experts were aware that Myriad's test missed some mutations, but the study might be "the most extensive effort to quantify how often that occurs," the Times reports (New York Times, 3/22). "Conventional tests are necessary but not sufficient," Mary-Claire King, co-author of the study and a UW geneticist, said, adding that women with family histories of the cancer should seek testing before the age at which the family member was diagnosed (Talan, Long Island Newsday, 3/22). "What (this study) really points to is that if women with a strong family history have been tested and have been told we didn't find a gene mutation, we shouldn't stop there," Julie Gralow, an oncologist at the Seattle Cancer Care Alliance, said. King added, "We need an open and competitive marketplace for the development of genetic testing" (Davidow, Seattle Post-Intelligencer, 3/22). Gregory Critchfield, president of the genetic testing division at Myriad, said the company's U.S. monopoly on the BRCA test has not hindered progress on testing, adding that the company hopes to introduce a more comprehensive test later this year (New York Times, 3/22).

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