Saliva test for prostate cancer

Simple at-home ‘spot test’ could help earlier diagnosis in men at high risk, meaning a greater chance of treating the disease successfully. 

The promising results of a medical trial are being shared at the annual meeting of the American Society of Clinical Oncology in Chicago. Researchers behind the BARCODE 1 study hope it could have a marked impact on prostate cancer.

Photo by Ibrahim Boran

In the UK, prostate cancer claims the lives of some 12,000 men each year – the second biggest death rate from cancer among men. Yet while there are very effective national screening programmes for other kinds of cancer, there is nothing of the sort for prostate cancer because the only existing option, a prostate-specific antigen (PSA) blood test is not sufficiently accurate. 

The new trial instead used saliva samples to check for small genetic changes linked to prostate cancer. More than 6,000 European men who were between 55 and 69 at the start of the trial – an age at which there is a higher risk of developing prostate cancer – were recruited through their GPs. Spit samples were then used to calculate prostate cancer polygenic risk scores (PRSs) based on 130 genetic variations that previous studies have shown to be linked with prostate cancer. 

Those with the highest 10% of risk scores were then invited to further screening. After an MRI scan and prostate biopsy, 40% of this high-risk group (187 in total) were diagnosed with prostate cancer. This is some 25% more than men identified through PSA tests as being at high risk. Indeed, 78% of the men diagnosed due to the new spit test (147 of them) were found to have ‘normal’ levels of PSA, which would have meant no further screening. 

What’s more, the spit test was less likely to falsely identify prostate cancer and detected a higher proportion of aggressive cancers (55% compared to 36%). In addition, a saliva test is relatively quick and easy to undertake – it could even be conducted at home. 

Ros Eeles, Professor of Oncogenetics at the Institute of Cancer Research and Consultant at the Royal Marsden NHS Foundation Trust – which jointly led the research – says: ‘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. 

‘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.’ 

For more about the trial, see Cancer Research UK.