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According to a new study by researchers at the University of Cape Town School of Medicine and Color Stanford University, a health services company that provides genetic testing.
The study of more than 700 people with one of the 30 mutations associated with cancer found that almost half of a patient's first-degree relatives (mother, father, siblings and children) chose to be tested lucky to have their own sequenced genes for around $ 50 – about a tenth of the standard cost. In addition, about 12% of people with the same mutation as the original patient then invited other members of their family to be screened.
Although not everyone with a cancer-related mutation is developing the disease, knowing that one is a carrier can help people and their doctors make informed decisions about breast cancer care. health when they are still healthy. For example, women with BRCA1 or BRCA2 mutations who have a significantly increased risk of developing breast cancer or ovarian cancer may choose to have a prophylactic mastectomy or have their ovaries removed. Other types of mutations, such as those that increase the risk of colon cancer, may indicate the need for more frequent or frequent screening.
"We found that this approach had been remarkably successful in overcoming traditional barriers to reaching and testing a patient's loved ones," said Allison Kurian, MD, associate professor of medicine and health policy and research at Stanford. "The results were very striking, as traditional approaches to cascading tests only lead to about 30% of family members being tested."
Kurian shares the title of the main author of the research, which was published on September 18 in the Journal of the National Cancer Institute, with Alicia Zhou, PhD, head of research at Color, based in Burlingame, California. Jennifer Caswell-Jin, MD, professor of medicine at Stanford, and Anjali Zimmer, PhD, color technical writer, are the lead authors of the study.
Increasing interest in genetic testing
Increasingly, newly diagnosed cancer patients are turning to genetic testing to understand why they have developed the disease. The discovery of a disease-associated mutation can help make therapeutic decisions and provide clues about the origin of cancer. But there is another important, often overlooked, benefit: test results can help healthy first-degree parents to assess their own genetic risk of cancer. It can be expected that nearly 50% of these parents will have the same mutation as the patient, even if they have not developed cancer themselves.
However, this type of cascade test, in which a cancer patient produces positive genetic test results among the patient's relatives, remains relatively rare – in part because doctors are often prohibited from contacting relatives of the patient directly. patient and own recent diagnosis may not immediately consider the implications for the health of their loved ones. Tests can also be expensive and are not always covered by insurance.
Since about half of the first-degree relatives of a patient are also likely carriers of the same mutation, cascade tests have important public health implications for early detection of cancer and even prevention.
Kurian and his colleagues wondered if there was an easier way to reach potential porters. They evaluated the first year of a family testing program in which people who harbored one of the 30 genes associated with cancer were encouraged to provide the test lab with email addresses for their first-degree relatives. . The laboratory then contacted the relatives to provide them with more information via a web portal and invite them to be screened for a cost of $ 50.
"One of the peculiarities of this study is that it does not focus on any gene," said Caswell-Jin. "These participants were carriers of mutations in 30 different genes, some of which are very strongly associated with the development of specific cancers. Since about half of a patient's first-degree relatives are also likely carriers of the same mutation, cascading tests have significant public health implications for early detection and even cancer prevention. "
To conduct the study, the researchers invited the carriers of one of the 30 cancer-associated mutations, identified by one of the many certified genetic testing laboratories, and their loved ones to participate in the program. family tests. They reached out to potential participants using online advertising, notices in doctors' clinics or group meetings for families with hereditary cancers.
From September 2016 to September 2017, 1,101 people – 741 Movers and 360 family carriers – chose to participate in the program. Together, the original participants then invited 2,280 members of their families to be tested. Nearly half of the invited individuals underwent self-testing during the follow-up period of the study.
As expected, about half of the tested parents were also carriers. About 12% of these people then used the family testing program to invite other family members to get tested.
"Although this was potentially lower than we expected, in many cases it was due to the fact that there were no more first-degree relatives in the family at all. test, "said Caswell-Jin.
Different mutations identified
Surprisingly, the researchers found that about 5% of the family members tested had cancer-related mutations that differed from those of their parents.
"These pathogenic mutations were totally unexpected and suggest that this might reflect the prevalence in the general population of known mutations associated with cancer," Kurian said. "This answers a long-standing question on the ground about what we could find if we systematically tested everyone.
The researchers point out that, regardless of how people are contacted for testing, it is important to use a genetic counselor to interpret test results and refer mutation carriers to appropriate health care services.
"It's such an exciting time," said Caswell-Jin. "We anticipate that the proportion of people undergoing genetic testing for mutations associated with the disease will continue to increase. We need to make sure they get the support they need to understand their results and encourage additional support and follow-up.
"We are very committed to learning the most effective way to implement genetic testing, especially in a large population," Kurian said. "We look forward to continuing this discovery and understanding how we can improve this new cascading test model."
Another author of the Stanford study is the senior genetic counselor Kerry Kingham. Kurian is a member of the Stanford Cancer Institute.
The research was supported by the BRCA Foundation, the Damon Runyon Cancer Research Foundation and Color.
Kurian has received research funding from Myriad Genetics for an independent project.
The Stanford Medicine and Health Research and Policy Departments also supported the work.
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