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It may seem inconceivable that a simple saliva test can tell you your chances of developing cancer.
But obviously it is possible. And the reason is crude but simple: Your genetic makeup can be found in your spitting.
Scientists are now able to extract DNA from cells – mainly leukocytes, also known as white blood cells – that float in your saliva.
This has already been demonstrated globally in popular genealogical tests of companies such as Ancestry.com and 23andMe, who can literally tell us where, and who we come from.
Now, a relatively simple saliva-based DNA test of 10 minutes can also identify variations on genes that identify men who are at highest risk of developing prostate cancer.
The test can also tell us about the risk of other cancers.
To this end, a group of scientists from the Institute of Cancer Research (ICR) in London has launched a clinical trial on a saliva-based DNA test to identify with greater clarity the most men to risk of developing prostate cancer.
Other than skin cancer, prostate cancer is the most common cancer in American men, according to the American Cancer Society.
And prostate cancer is the most commonly diagnosed cancer among men in Europe, according to the Joint Research Center (JRC), the European Commission's (EU) science and knowledge service.
The ICR study follows the results of a study published in the journal Nature Genetics of over 140,000 men who identified 63 new genetic variations in the DNA code that increase the risk of cancer of the prostate.
"The British study has pioneered prostate cancer research," said Jonathan Simons, executive director of the Prostate Cancer Foundation (PCF), the world's largest prostate cancer organization. .
"But there is much more to learn about younger men who have more aggressive cancers earlier," said Simons, a medical oncologist and internationally recognized leader in prostate cancer research.
Dr. Iain Frame, research director at Prostate Cancer UK, said in a statement: "This new study could help men understand their individual genetic risk of prostate cancer, which could prompt them to talk about their disease.
Saliva tests already on the market
Saliva testing for prostate cancer patients is an important development in what has been called precision medicine, which simply means customizing treatments for individual patients based on their genetic makeup.
Several saliva-based DNA tests have already been approved in the United States by the Food and Drug Administration (FDA).
They must always be ordered by a doctor.
When Simons decided to test himself for a possible predisposition to prostate cancer, he chose the saliva test that he received in the mail.
"I wanted to understand the patient's experience regarding saliva testing for genetic risk for prostate cancer.I ordered a test with a credit card and took it." myself, "he said.
The test is simple. The instructions are simple. Simply spit in the plastic tube provided, seal it and send it back.
After a few weeks, you will receive a report that tells you whether genetic mutations have been identified or not.
The test in which Simons participated, which examined 31 genes, showed no mutation. Which means that he does not fall into the high risk group.
"I learned from this saliva test that my risk of prostate cancer is the same as that of the general population, and the risk of prostate cancer for my sons is the same," she said. he says.
Mr. Simons said the test report also gave him the option of contacting a genetic counselor.
If someone has mutant genetic markers, he says, the patient is then traversed by what the results mean, first by an urologist, then by a genetic counselor.
A genetic counselor is a person with a genetic background who explains to the patient what was found on the test and what are the implications for the patient and the family in terms of risk of disease.
"The genetic counselor is here to answer the patient's questions [the] patient a plan of life, "said Simons.
The test can help prevent cancer
The saliva test is attracting more and more attention from researchers and clinicians recognized in the field of cancer nationally and internationally.
Dr. Heather Cheng, director of the Seattle Cancer Care Alliance's Prostate Cancer Genetics Clinic, is conducting an ambitious clinical trial on saliva testing in Washington State.
"Salivary testing for a better understanding of hereditary cancer risk is another good option with blood tests, and can help men learn vital information that can help doctors make medical decisions," Cheng said. assistant professor. at the University of Washington School of Medicine and an associate member of the Fred Hutchinson Cancer Research Center.
"This may be especially true for men with advanced prostate cancer that has spread to the outside of the prostate," she said.
Cheng said that it is "extremely important" for people to understand that there are different types of saliva tests available.
Some, like Ancestry.com and 23andme, are recreational and not for health care, while others are certified medical tests.
"When a person is looking for medical grade information, she should have a conversation with her doctor and / or genetic counselor in order to have the best understanding of the risks and benefits before doing the test", Cheng explained.
The fact that these tests are becoming more accessible to the public and gives us a better idea of our genetic make-up and cancer risk is a significant breakthrough for patients.
In addition, as researchers now know that some men with prostate cancer have these genetic mutations and that they are gaining more specific knowledge on this subject, new treatments are being developed to treat prostate cancer and Other cancers.
Exploiting the body's immune system provides long-term remissions and even cures in many types of cancer, including Hodgkin's and non-Hodgkin's lymphoma, melanoma, and lung cancer.
While immunotherapy has not yet been optimized in prostate cancer, things are moving in that direction.
Last year, the FDA approved Merck's Keytruda immune checkpoint inhibitor for the treatment of all solid tumors with so-called MMR or MSI mutations, including cancer of the prostate.
The more researchers learn about our genetics, the more specific and effective these treatments will be.
Ros Eeles, Ph.D., professor of oncogenetics at the ICR, said in a press release, "If we can tell from the DNA that it is likely that & # 39; A man will develop prostate cancer, the next step is to see if we can use this information. to help prevent the disease. "
New subtype of prostate cancer
Study funded by the Prostate Cancer Foundation published this month in the journal Cell identified a new subtype of advanced prostate cancer in approximately 7% of patients with advanced disease.
The subtype is characterized by the loss of the CDK12 gene. It was found that it was more common in metastatic prostate cancer than in the case of early-stage tumors that had not spread.
Tumors in which CDK12 was inactivated were sensitive to immune checkpoint inhibitors, which are a type of immunotherapy treatment that, to date, has had only limited success in the Prostate cancer.
"Because prostate cancer is so common, 7 percent is a significant number.The fact that immune checkpoint inhibitors can be effective against this subtype of prostate cancer makes it even more significant," said Dr. Arul Chinnaiyan, senior author of the study and director of the Michigan Center for Translational Pathology.
"It's an exciting prospect for patients who have CDK12 alterations and can benefit from immunotherapy," he added.
Howard Soule, Ph.D., executive vice president and scientific director of the Prostate Cancer Foundation, said in a statement: "This very promising study suggests that the loss of CDK12 could be a biomarker for identifying patients with cancer. prostate.
He added: "The Prostate Cancer Foundation is proud to have funded this team, which continues to make fundamental progress in identifying exploitable genomic mutations in prostate cancer and utilizing it. information to identify new classes of precision processing. men with prostate cancer. "
Positive predictions
Simons told Healthline that if there was a mutation in the CDK12 gene, and that the patient's cancer had a mutation in the second copy of the tumor, "this confers a very high probability of a remission complete with immunotherapy ".
Simons predicted that within five years, "every urologist will have an application for this and will work with patients and will involve a genetic counselor. Genes do not have to be fate. "
Still in the very near future, he said, "Saliva tests will become an essential companion to the PSA test. The PSA test is also important, and gives us information that the saliva test does not do. But soon both tests will be essential. "
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