New Spit Test Predicts Prostate Cancer Risk

Prostate cancer. Source: NHGRI

It turns out that our spit is holding information about our potential future health. This new spit test detects genetic variants that help to identify men who have an increased risk of developing prostate cancer. But could this $100 spit test replace the blood-based Prostate-Specific Antigen (PSA) test currently used to monitor prostate cancer?

A study published in Nature Genetics compared half a million SNPs (Single Nucleotide Polymorphisms i.e. single base changes) in the DNA of 80,000 prostate cancer patients against the DNA of 61,000 men without the disease. This identified the variants that are likely to be associated with the disease.

Recent work has also linked prostate cancer with high levels of iron in the body.

This Gene Could Be the Link Between Iron and Prostate Cancer

More than 100 of these SNPs predicting for prostate cancer occurrence were already known, but the new study adds another 63, making the predictions scientists can make with any test much stronger and more reliable. Many of the new variants found were in genes that regulate communication between cells of the immune system and other cells in the body or DNA repair, which could have future implications for treatment with immunotherapies for these patients.

“If we can tell from testing DNA how likely it is that a man will develop prostate cancer, the next step is to see if we can use that information to help prevent the disease,” said Eeles.

The research, funded by an international team including the world’s two biggest cancer research agencies, the National Cancer Institute (NCI) and Cancer Research UK, found that 1-in-10 had a 25% chance of developing the prostate cancer. 1-in-100 men had a 50% chance of developing the disease.

There are plans to implement the genetic test within UK healthcare services, following studies that will be carried out with primary care physicians in the UK to validate the accuracy and effectiveness of test with primary care physicians in the UK.

“We are interested in doing similar trials to the UK and are aiming for within the next year or so,” said Fredrick Schumacher, lead author of the study and Associate Professor in the Department of Population & Quantitative Health Sciences at Case Western Reserve University in Cleveland.

However, as with a lot of studies there remains heavy bias towards using data from European descent; an issue that has been addressed by our panel of experts on our monthly panel show, The Genome Spot (register to watch on demand). This study bias ultimately prevents the test being used in the US where the population is more multi-ethnic.

“We have more of a multi-ethnic population here in the U.S. We need to validate the test in African-American populations, particularly, as we know they are twice as likely to develop prostate cancer as people of European descent,” said Schumacher.

Schumacher and collaborators from the University of Southern California are currently in the process of analyzing data from 20,000 African American men to figure out whether the test is also useful for them and he stresses the importance of also looking at data from men from Latino and Asian American descent to ensure any test would be useful.

If you’re interested in other uses of saliva in genetic studies, you can register for our upcoming webinar looking at whole genome sequencing with direct saliva input!