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Mar. 27--At 44, Peg Nichols wonders whether she carries the same genes responsible for a family legacy of breast cancer that led four generations of her loved ones to undergo double mastectomies.
She sees a breast surgeon twice a year, gets an annual mammogram (starting when she was 28) and is considering having her blood screened for genes that carry a higher risk of breast cancer. Her great-grandmother, grandmother, mother and sister were all in their 30s and 40s when diagnosed. Her father's sister developed breast cancer in her 30s.
"I want to do genetic screening," said Nichols, who lives in Washington, D.C.
But last week's study in the Journal of the American Medical Association showing that conventional tests in the United States can miss mutations that fall outside of the most common ones may make people like Nichols reconsider the $3,000 testing.
"These are very personal and individual decisions," said Dr. Larry Norton, medical director of the Breast Cancer Center at Memorial Sloan-Kettering Cancer Center in Manhattan. "These are very high-risk families. But there are other families who may also be high-risk but don't know the family's history or don't have a lot of women in them."
In the JAMA study, Mary-Claire King and colleagues at the University of Washington in Seattle reported finding new mutations in 12 percent of 300 breast cancer patients studied - all of whom tested negative for the most common five genetic mutations, including BRCA1, BRCA2 and BRCA1-5382. Another 5 percent had other disease genes not picked up in routine testing.
The conventional test, developed and sold by Myriad Genetics, is sensitive in picking up mutations among Ashkenazi Jews, where the mutations were first identified.
For non-Jewish women like Nichols, the gap in testing raises questions.
Myriad spokesman William Hockett said the company is developing a more advanced test that will be available by the end of the year.
Norton and King agree that women at high risk should develop a relationship with a genetic counselor or clinical geneticist. "Genes don't change, but technology does," Norton said. "As the technology evolves, you can have an ongoing discussion."
Preventive removal of both breasts is a sure way to avoid cancer, but there are other things high-risk women can do, including frequent cancer screening. Studies have also shown tamoxifen, a hormone-based drug, taken for five years can reduce risk by 50 percent. Birth control pills after a woman has completed her family can also reduce risk for breast and ovarian cancer. Women with a family history of ovarian cancer can also opt to have their ovaries removed.
King said that among Ashkenazi Jewish women, 1 percent carry the ancient BRCA1 mutation, another 1 percent the BRCA2 mutation and 0.5 percent a third mutation called BRCA1-5382, the most common mutation throughout Europe among non-Jewish families.
In Europe, tests pick up a wider number of mutations, King said. She thinks Ashkenazi women diagnosed with breast or ovarian cancer should think about genetic testing, as well as non-Jewish families with many affected relatives.courtesy of the university of Washington
Mary-Claire King's study found new defects in 12 percent of women who had tested negative for common genetic mutations.
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