Boston- A heated discussion broke out today at the annual meeting of the American Society of Human Genetics on a hot topic -button: When will we know enough about the risk of rare cancer genes begin to systematically test for them in patients with a family history of cancer
on one side of debate was a team led by geneticist Mary breast cancer -Claire king, who discovered the first risk gene for hereditary breast cancer, BRCA1 . The King group now wants to regularly test some women for other genes linked to cancer. Other researchers, however, have argued that it is premature to test these other genes, which are less well understood.
Physicians often offer women with breast cancer in their family to test for mutations in BRCA1 and a related gene, BRCA2 . If the tests are positive, some women can take preventive measures. Earlier this year, for example, actress Angelina Jolie drew widespread attention for his decision to have a double mastectomy because she inherited a version of BRCA1 which carries a risk of developing breast cancer by 87%
Many women with breast cancer in their family, however, do not test positive for the BRCA mutations ,. At the meeting, Tomas Walsh of the University of Washington, Seattle, reported a test he and King developed, called Broca, as sequences not only BRCA genes, but also about 38 other genes cancer risk. They ran the test on BROCA nearly 2,300 women from 743 families with breast cancer. In 77 families, they were not BRCA mutations, but find changes in other genes they say are definitely linked to breast cancer, such as TP53 and CHEK2 . Another 41 families carried mutations in a larger set of genes whose role in cancer is "emerging," said Walsh.
King and Walsh are not just using their BROCA test in research, however, the university is also offering it as a clinical test for patients. And doctors also can order the commercial test.
This did not sit well with other researchers in the meeting today. "It is irresponsible and unacceptable" in the clinical trial for other genes that BRCA for which the risks are not well established, said Nazneen Rahman of the Institute for Research on Cancer in Sutton , United Kingdom do is "harmful" she said science Insider, because it could cause women to take drastic measures such as having their breasts removed. the King team "mixed research clinical "tests, she said.
King defended their test group in a discussion with reporters. Doctors receive results for 12 genes that evidence suggests can double or quadruple the risk of cancer; this means a chance of a woman developing breast cancer of 25% to 50%, Walsh said. When the team detects these genes, they did not recommend surgery, but screening at regular place with imaging.
King emphasizes that screening BRCA1 was controversial before the community consensus in 1997. "I have a sense of déjà vu," she said science Insider. She said her critics mistakenly think the returns BROCA clinical test results for 40 genes, not just 12. "We are comfortable on those where we already have data," on the basis of their own studies and literature, she said. "We were extremely careful not to report variants" of uncertain significance, she said.
Surgeon Greta Bernier, King group added that during the test only BRCA genes is recommended by the National Comprehensive cancer network, which issues guidelines for the treatment of cancer, his team is confident that the network will soon add other genes on their list. it stresses also doctors can already order tests for the genes on the list of gene-testing companies around.
Melissa Southey from the University of Melbourne in Australia believes that while it is important to test all the cancer risk genes in the research, evidence for clinical trials is strong enough for a small number of genes, and even then only for some specific variants. The problem, she says, is that most other variants are so rare that it may never be possible to study enough people to identify risks. Instead, researchers have to rely on other evidence that mutations are harmful, such as laboratory studies of the proteins encoded by genes.
The same difficulty confronting geneticists as they discover other genetic variants of risk rare, Southey says. "This is the edge, where we are," she said. "We have a lot of information, but not enough to offer advice."
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