Prostate cancer is one of the primary health scares for aging men, but thankfully, improved testing could soon be on the way. A simple spit test that can be taken at home is among the most promising methods for detecting prostate cancer, which an estimated 1 in 8 men are diagnosed with during their lifetime.
In an April 2025 study published in the New England Journal of Medicine, researchers demonstrated the success of calculating prostate cancer risk from saliva. The study showed that a spit test can identify prostate cancer more accurately than prostate-specific antigen (PSA) tests, which have come under scrutiny for their tendency to produce unreliable results.
Success of the PRS Saliva Test
The study assessed 6,142 European men between the ages of 55 and 69, extracting germline DNA from their saliva. Using the saliva, researchers were able to find a polygenic risk score (PRS); this metric denotes someone’s risk of developing a disease — in this case, prostate cancer — based on the genetic variants they contain.
Those with a PRS in the 90th percentile or higher were invited for further screening, since a higher score indicates the inheritance of many genetic variations that could raise the risk of developing prostate cancer.
A total of 468 participants with exceptionally high PRS underwent MRI scans and prostate biopsies; 187 of these men (40 percent) were diagnosed with prostate cancer as a result.
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The Flaws of PSA Blood Tests
Unlike the PRS test using saliva, PSA blood tests can fall short in several ways. These tests measure prostate-specific antigen, a protein produced by both normal and malignant cells from the prostate gland.
An initial PSA test is often recommended to men around age 50 who have an average risk of developing prostate cancer, or men around age 40 who have a high risk due to family history. The American Cancer Society states that men with a PSA of less than 2.5 ng/mL may only need to be retested every two years, whereas testing should be done every year for those with a higher PSA (for reference, 4.0 ng/mL is considered abnormal for PSA levels).
Although PSA tests are still commonplace in prostate cancer screenings, they don’t always produce the desired outcome for patients.
According to a press statement on the new study, PSA tests falsely indicate “prostate cancer in men three out of four times.” False-positives derived from the tests could lead patients to seek unnecessary medical procedures. A separate 2022 study found that age, alcohol intake, and the presence of urinary tract infections were commonly associated with false positives in PSA tests.
Another downfall of PSA tests is that they often detect other cancers that normally grow slowly and would never show symptoms of concern.
The new study showed that PRS spit tests, on the other hand, are able to catch a higher proportion of aggressive cancers that are likely to spread.
Expanding Knowledge on Prostate Cancer
Researchers are now working to develop a version of the test that can detect more prostate cancer risk variants in other populations, such as those with Asian and African ancestry. They will also continue with additional trials to compare the success rate of spit tests with MRI scans and PSA tests.
“Early detection of cancers significantly increases the chance of a cure. With prostate cancer cases expected to double by 2040, it’s crucial to establish a robust way of picking up clinically significant cases of prostate cancer at an earlier stage,” said Kristian Helin, Chief Executive of The Institute of Cancer Research in London. “The current PSA test often leads to unnecessary treatments and, more concerningly, fails to detect some cancers. There is an urgent need for a better screening test. This research represents a promising advancement towards that goal and underscores the life-saving potential of genetic testing.”
This article is not offering medical advice and should be used for informational purposes only.
Read More: Early Prostate Cancer Diagnosis Soon Possible with Simple Urine Sample
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Jack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine.
