12 Jun 2018
This article is more than 3 years old

Behind the Headlines: The prostate cancer 'spit test'

Across the papers today is news of a 'spit test' to help diagnose prostate cancer. It’s a promising step forward in genetics, but we still need better tests for diagnosis.

So what’s new?
Researchers have just announced that they’ve found 63 new genetic variation in men’s DNA that affect their risk of prostate cancer. They've combined these with more than 100 others that we already know about to create a saliva test that works out if a man is at high risk or low risk of the disease.

How could this test be used?
It could help doctors to better understand the results of a man's PSA test and identify who is most at risk of developing the disease. These individuals could then be screened more regularly. The researchers are now planning to use this test in a trial to see if it can help to save lives. This means that the test isn’t publicly available yet.

What does high risk mean?
Imagine 100 men lined up based on their score on this test, with risk of prostate cancer increasing from left to right. The man furthest right with the highest risk would have almost six times higher risk than the man in the middle. This is very high risk, meaning this man and his doctor might need to consider close monitoring.

The men just to the left of him, numbers 90 to 99, would have a 2.5 times greater risk. While this risk is high, it is similar to the risk faced by black men and men with a family history. For these men in these groups, we recommend speaking to their GP and being aware of their risk and potential symptoms

How important are your genes?
Prostate cancer is one of the most genetically heritable forms of cancer, so it's important that we understand their role. We know from studies of twins that about half of your prostate cancer risk comes from your genes. The rest of your risk comes from lifestyle and environment, although these aren’t fully understood.

There isn’t a single gene for prostate cancer that means you’ll get the disease. Instead, there are hundreds of genetic changes that each have a very small effect, but together can add up. It has taken decades of research to uncover the complexity of prostate cancer genetics, so it's good to see this coming close to having a benefit for men.

Why can’t everyone get screening?
What we need is better tests for actually diagnosing prostate cancer, then everyone could get regular screening. Current tests miss too many cancers, lead to too many unnecessary biopsies and pick up cancers that would never have caused any harm. We’re working to develop better tests, which include combining genetics with blood tests and the latest scans, so that we can get the screening programme that men need.