Wider Genetic Screening For Breast Cancer?
Geneticist Mary-Claire King of the University of Washington, responsible for the identification of the first breast cancer genes BRCA1 and BRCA2, is recommending that all women get tested for genetic mutations that can cause breast cancer.
Women who have mutations in these genes are much likely to get breast cancer and ovarian cancer, with 5 to 10% of all breast cancers caused by BRCA mutations, according to the National Cancer Institute.
In a study entitled “Population-Based Screening for BRCA1 and BRCA2” published in the latest issue of the JAMA journal, Dr. King and colleagues generated controversy by suggesting that all adult women should be screened for defined categories of BRCA1 and BRCA2 mutations, specifically on unambiguously loss-of-function mutations with definitive effect on cancer risk.
“My colleagues and I are taking a really bold step. We’re recommending that all adult women in America, regardless of their personal history and regardless of their family history, be offered genetic testing for the breast cancer genes. The difficulty with that approach is that it misses identifying some women who have mutations in these genes,” Dr. King said in an NPR interview.
However, criticism was quick to arrive, with field experts saying that one study is not enough evidence to know if these women indeed face a higher risk of developing breast cancer, and that universal testing could result in women undergoing unnecessary surgery. Furthermore, questions regarding screening were also raised, such as analytic validity (do tests reliably and consistently measure the mutations?), clinical validity (what’s the accuracy of a positive test to predict breast cancer development? Can a negative test be reliable t assume a patient is not at risk due to a BRCA mutation?), clinical utility (does a positive test provide actionable information) along with ethical, legal and social implications.
In response, Dr. King told the New York Times “Critics may object that ‘women aren’t ready for this.’ But why should women be protected from information that will empower them and allow them to control their lives? We don’t need that kind of protection.”
One of the reasons that no one had recommended screening all women so far is because no one knew how dangerous the mutations were for the average woman.
With this in mind, King and colleagues designed a study where they identified more than 400 women who were carrying the mutations even though they had no family history of breast cancer.
The work, entitled “Population-based screening for breast and ovarian cancer risk due to BRCA1 and BRCA2” and published in the Proceedings of the National Academy of Sciences (PNAS) concluded that women who carried one of these mutations had the same high risks of developing either breast or ovarian cancer as those who are identified because of their family history.
“Women who do learn they have a mutation that’s comparable to Angelina Jolie’s and confers very high risk can begin to think about what that means and be referred to a high-risk clinic to develop a prevention plan” Dr. King told the New York Times.
However, Dr. Fran Visco, president of the National Breast Cancer Coalition, is not yet convinced that these new data are sufficient to make definite claims, and he argues that just because a woman has one of these mutations doesn’t mean she’ll definitely get cancer.
“These are very serious surgeries that women have to undergo. Removing their breasts. Removing their ovaries. We’re talking about surgery to remove healthy body parts. If we give women this message, we may very well end up doing more harm than good,” Dr. Visco told NPR.
Additionally, screening tests can cost hundreds to thousands of dollars depending on insurance coverage.
Nonetheless, this type of genetic information could potentially lead women who are diagnosed with BRCA1/2 mutations to develop habits that could modify the risk for breast cancer development, such as regular MRIs to try to catch any cancer early, eat healthy, practice exercise, having children and breast-feeding children. All of these could help prevent the chances of having breast cancer, even if certain women start off with a genetic disadvantage.
Posted by: Ana de Barros September 10, 2014, Bio News Texas
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