On an ordinary day in Brighton, Dheeresh Turnbull swabbed the inside of his cheek for science. He was healthy, with no symptoms and no family history of prostate cancer. He felt fine. Yet the results from the spit test he mailed back would soon reveal something unexpected: a life-threatening tumor was growing inside him.

That test, developed by scientists in the UK, may soon change how we detect the most common cancer in men.

A Better Way to Spot Risk

Prostate cancer is notoriously difficult to screen for. Its current standard test—known as PSA, or Prostate Specific Antigen—relies on measuring a protein in the blood. But PSA tests often miss aggressive cancers and lead to false positives in men who don’t need treatment. As a result, some undergo invasive procedures for tumors so slow-growing they pose little threat or miss out on early detection.

Researchers at The Institute of Cancer Research (ICR) and The Royal Marsden National Health Service (NHS) Foundation Trust believe they’ve found a better approach.

Their study, published in the New England Journal of Medicine, tested over 6,000 men aged 55 to 69 from GP surgeries across the UK. Instead of searching for the cancer itself, the new test calculates what scientists call a polygenic risk score (PRS)—a measure of inherited risk based on 130 genetic variants found in saliva.

Men in the top 10% of risk scores were invited for further screening. Of the 468 who took part, 187 were found to have prostate cancer. That’s 40%—a detection rate notably higher than PSA testing, which finds cancer in about 25% of high-PSA men.

More crucially, over half of those cancers were aggressive, the kind most likely to spread and kill.

“This test could turn the tide on prostate cancer,” said Prof. Ros Eeles, who led the study. “We have shown that a relatively simple, inexpensive spit test to identify men of European heritage at higher risk due to their genetic makeup is an effective tool to catch prostate cancer early.”

What the PSA Test Misses

Many of the cancers uncovered in the study would have not been detected by current methods. Of the 187 men diagnosed, 118 had PSA levels below the NHS threshold of 3.0 micrograms per liter—considered “normal.” Under existing guidelines, they would have been sent home with no further tests.

In fact, MRI scans failed to detect cancer in 64% of those men, even when tumors were confirmed by biopsy.

“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,” said Eeles.

Current PSA testing isn’t routinely offered in most countries. The test produces false positives in about three out of four cases. This leads to follow-up procedures, including biopsies, that may not be needed—and which can result in side effects like incontinence and sexual dysfunction.

Kristian Helin, CEO of the ICR, told The Guardian: “The current PSA test often leads to unnecessary treatments and, more worryingly, fails to detect some cancers. There is an urgent need for a better screening test.”

Lives Already Saved

For Dheeresh Turnbull and other people like him, the test meant catching cancer that would have remained hidden. After his diagnosis, his younger brother Joel—still too young for traditional screening—also took the spit test. He, too, had an aggressive prostate tumor.

“Because of this study, two lives have now been saved in my family,” Dheeresh said.

While the test is not yet available for routine use, scientists are optimistic. The £42 million TRANSFORM trial, partially led by the same research team, is now underway to compare the spit test directly with PSA and MRI.

Prof. Michael Inouye of the University of Cambridge called the findings “a landmark” and predicted we will look back on this study as a turning point in using genetics for cancer screening.

But there are still hurdles. The study focused only on men of European ancestry. Work is underway to adapt the test for men of African and Asian descent—groups who are also at high risk. Black men, in particular, are twice as likely to develop prostate cancer and more likely to be diagnosed at later stages.

Prof. Dusko Ilic from King’s College London cautioned that while the findings are promising, the test improved detection only “modestly” and does not yet prove better survival outcomes. “This is a big step along the path to clinical implementation, but it is still a long road.” he said told BBC.

Despite the limitations, experts believe genetic testing could pave the way for smarter, more targeted cancer screening—avoiding the pitfalls of blanket approaches while saving lives.

If the larger trials confirm these results, health services may one day offer genetic spit tests alongside PSA and MRI and catch thousands of prostate tumors earlier.