Prostate cancer is exceedingly prevalent in men: It’s the second most commonly diagnosed cancer and the fifth leading cause of cancer death among males worldwide. One of the standard steps to identify those at risk for the disease requires a trip to the doctor and a blood test, which looks for elevated prostate-specific antigens, or PSAs — proteins produced by prostate gland cells.
But a new, inexpensive screening method may be more accurate and better able to detect prostate cancer earlier, and can be completed in seconds at home via a self-collected saliva sample that is then sent in for analysis. Furthermore, the test could better identify more aggressive forms of the disease and prevent men with lower risk from undergoing unnecessary treatment.
At an annual meeting of the American Society of Clinical Oncology, held May 31-June 4 in Chicago, researchers out of the U.K. presented the results of a trial of the DNA-based test, which looks at genetic variants associated with prostate cancer.
“With this test, it could be possible to turn the tide on prostate cancer. We have shown that a simple, cheap, spit test to identify men at higher risk due to their genetic makeup is an effective tool to catch the cancer early,” Ros Eeles, professor of oncogenetics at London’s Institute of Cancer Research, or ICR, said in a statement.
She noted that the test builds on decades of research into the disease’s genetic markers, adding: “Our study shows that the theory does work in practice — we can identify men at risk of aggressive cancers who need further tests, and spare the men who are at lower risk from unnecessary treatments.”
For the trial, called Barcode 1, scientists from the ICR and The Royal Marsden NHS Foundation Trust enlisted 6,142 European men ages 55-69 and used the spit test to calculate a polygenic risk score for each of them. The score is based on 130 genetic variations in DNA code that have been linked to prostate cancer.
The men with the highest 10% of the risk scores underwent an MRI and a biopsy to confirm or rule out the presence of cancer. Of those who received further screening following the spit test, 40% were diagnosed with the disease. Conversely, only 25% of men who are found to have elevated PSA levels via the standard blood test will actually be diagnosed with the disease.
Additionally, the saliva test was found to be more accurate than an MRI scan alone for men with a high genetic risk. It also identified a higher proportion of aggressive forms of the cancer than PSA tests did.
“Cancers that are picked up early are much more likely to be curable, and with prostate cancer cases set to double by 2040, we must have a program in place to diagnose the disease early,” said Kristian Helin, chief executive of the ICR. “We know that the current PSA test can cause men to go through unnecessary treatments and, more worryingly, it’s missing men who do have cancer.”
He continued: “We urgently need an improved test to screen for the disease. This research is a promising step towards that goal, and it highlights the role that genetic testing can play in saving lives.”
The next step is to determine whether the genetic markers associated with prostate cancer in European men are also present in other populations, “to ensure this test can benefit all men,” Helin added.
Dheeresh (right) and his brother Joel (left) in 2022
Two men who have already benefited from the test are Dheeresh Turnbull and his brother Joel. Dheeresh was initially enrolled in the trial, and was subsequently diagnosed with the disease, prompting him to get Joel involved as well.
“I was completely shocked when I received my diagnosis as I had absolutely no symptoms at all, so I know I would never have been diagnosed at this stage if I hadn’t joined the trial,” said Dheeresh, 71.
“Because the saliva test revealed that I had a high genetic risk of developing the disease, my younger brother, who would have been too young to join the study directly, signed up and discovered that he also had an aggressive tumor in the prostate,” he went on. “It’s incredible to think that because of this study two lives have now been saved in my family.”
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