Spit test ‘better than blood test for men with genetic prostate cancer risk’

Early research raises hopes of a more accurate screening tool for men who are at high risk of aggressive disease.

A prostate cancer spit test is better for men with higher genetic risk than a standard blood test, research suggests
A prostate cancer spit test is better for men with higher genetic risk than a standard blood test, research suggests (David Davies/PA)

At-home spit tests are better than the standard blood test for identifying men who have a high genetic risk of developing aggressive prostate cancer, early research suggests.

The preliminary findings, presented at the American Society of Clinical Oncology (ASCO) annual meeting in Chicago, raise hopes of a potentially more accurate screening tool for a disease that claims around 12,000 lives a year in the UK.

There is currently no national screening programme for prostate cancer and the standard blood test, which measures levels of a protein called prostate-specific antigen (PSA), is not accurate enough.

The saliva test, where the sample can be collected at home, looks for genetic variants linked to prostate cancer.

For men with a high genetic predisposition to the disease, spit analysis was more accurate than the PSA test as an early assessment tool, the researchers at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust said.

The team said its research could help “turn the tide on prostate cancer” by offering a cheap and easy-to-use spit test to catch the disease early and save thousands of lives.

It could also spare many others who are at lower risk from unnecessary and invasive treatments, the researchers added.

The BARCODE 1 study recruited 6,142 European men aged 55-69 from their GP surgeries.

The men were deemed to be at an age where the risk of prostate cancer is increased.

The researchers calculated the polygenic risk score – which is based on 130 genetic variations in the DNA code linked to prostate cancer – of all those taking part.

Those with the highest risk scores – 558 men who carried many of these variants – were invited for further screening.

The team found the saliva test gave fewer false positive results and picked up a higher proportion of aggressive cancers than the PSA blood test.

Following an MRI scan and biopsy, 40% of men with high scores from the saliva test were diagnosed with prostate cancer.

In case of PSA tests, only 25% of men with a high PSA level will actually have prostate cancer, the researchers said.

This is because the PSA test is not accurate enough and can falsely indicate cancer in men three out of four times.

It can also miss cancers that require urgent treatment and detect ones that are unlikely to ever be life-threatening.

Professor Kristian Helin, chief executive of ICR said: “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 programme in place to diagnose the disease early.

“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.

“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.”

Naser Turabi, director of evidence and implementation at Cancer Research UK, said: “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.”

Katie Willis, daughter of Bob Willis, former England cricket captain who died from prostate cancer, and co-founder of the Bob Willis Fund which provided some funding towards the research, said: “Although the PSA test is effective for some, it did not work for Bob.

“If this research can save even one life, establishing the fund would have been a worthwhile endeavour for our family.”

Dheeresh, 71, from Brighton, was diagnosed with prostate cancer three years ago while taking part in the trial.

He underwent surgery to remove part of his prostate at The Royal Marsden and is currently doing well.

He said: “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.

“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 tumour in the prostate.

“It’s incredible to think that because of this study two lives have now been saved in my family.”