An at-home saliva test that assesses genetic risk of prostate cancer is more accurate at detecting clinically significant disease than prostate-specific antigen (PSA) level or magnetic resonance imaging (MRI), UK researchers have reported.
The test developed at the Institute for Cancer Research provides men with a polygenic risk score on the bases of 130 gene variants known to be associated with in increased chance of prostate cancer.
A UK trial of the test in men aged 55-69 years found it was better at detecting disease that required treatment than PSA testing and had fewer false positives, the researchers reported in the New England Journal of Medicine.
It also accurately identified men with prostate cancer that was missed by an MRI scan.
A total of 6,393 participants had their polygenic risk score calculated using the test. Of those, 745 had a risk score in the 90th percentile or higher and were invited to have further screening.
The researchers said 468 underwent MRI and prostate biopsy, with cancer detected in 187, equating to 40%.
By comparison, 25% of men with a high PSA level will actually have prostate cancer, they said.
Of the 187 men who were found to have cancer, 118 (63.1%) had a PSA level below 3.0ug/L, which would usually indicate that no further screening is required.
Results showed 55% (n=101) of this group had an intermediate or higher risk of cancer that indicated treatment, but in 74 of those their cancer would not have been detected by current screening approaches of PSA test followed by MRI.
Overall, 125 men had prostate cancer confirmed by a biopsy that was not detected by the MRI.
The team also found 40 patients with aggressive cancers they otherwise would not have known about.
The researchers said the saliva test could offer an additional screening tool to be offered to men at higher risk of prostate cancer, or those presenting with symptoms.
Future studies will follow-up the men with high scores to monitor if they go on to develop prostate cancer. The test has also been updated after more variants were detected in men of Asian and African ancestry.
Last week, health secretary Wes Streeting week told MPs he wants to see a national screening programme for prostate cancer for men at high risk but that it must be evidenced based.
The National Screening Committee is currently evaluating several options for a targeted approach.
Evidence collection includes the UK TRANSFORM trial, which is directly comparing the saliva test to PSA and MRI scan, to assess whether those with a low genetic risk may benefit from an alternative screening tool.
Professor Ros Eeles, professor of oncogenetics at the Institute of Cancer Research and consultant in clinical oncology and cancer genetics at The Royal Marsden NHS Foundation Trust, said: ‘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.
‘Building on decades of research into the genetic markers of prostate cancer, 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.’
Naser Turabi, director of evidence and implementation at Cancer Research UK, said: ‘Right now, there’s no reliable method to detect aggressive prostate cancer, but this study brings us a step closer to finding the disease sooner in those people who need treatment.
‘It’s encouraging to see that genetic testing might help to guide a more targeted approach to screening based on someone’s risk of developing prostate cancer.
‘More research is now needed to confirm if this tool can save lives from the disease so that it can be rolled out to improve diagnosis.’
A version of this article was originally published by our sister publication Pulse.
