At-Home Saliva Test Shows Promise in Prostate Cancer Detection

A new at-home saliva test could revolutionize prostate cancer screening, offering a more accurate and less invasive alternative to the current standard blood test. The innovative test analyzes a man's DNA for specific genetic variants, potentially reducing false positives and identifying aggressive cancers earlier.

The Limitations of PSA Testing

For years, the prostate-specific antigen (PSA) blood test has been the primary method for detecting prostate cancer. However, the PSA test has significant limitations. It frequently produces false positive results, leading to unnecessary anxiety, MRI scans, biopsies, and treatments. In fact, studies show that the PSA test falsely indicates prostate cancer in men three out of four times. Furthermore, it often detects slow-growing cancers that are unlikely to pose a life-threatening risk, resulting in overtreatment.

A Spit Test for Genetic Risk

Researchers at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust have developed a new approach: a saliva-based test that assesses a man's polygenic risk score (PRS). This test analyzes 130 genetic variants known to be associated with an increased risk of prostate cancer. By examining DNA extracted from saliva, the PRS test aims to identify men at higher risk more accurately than the PSA test. The saliva test can be easily administered at home, eliminating the need for a doctor's visit.

Superior Accuracy and Early Detection

The BARCODE 1 study, published in the New England Journal of Medicine, demonstrated the effectiveness of the PRS test. The study found that for men with the highest genetic risk scores, the saliva test was a better tool than the PSA test. The PRS test falsely identified fewer people with prostate cancer, picked up cancers missed by the PSA test alone, and detected a higher proportion of aggressive cancers. In one study, the PRS saliva test identified 55.1% of aggressive cancers, compared to only 35.5% identified by the PSA test. The test also accurately identified men with prostate cancer that was missed by an MRI scan.

Real-Life Impact

The new test has already had a tangible impact on individuals and families. Dheeresh Turnbull, a participant in the trial, discovered he had a life-threatening tumor thanks to the spit test, despite traditional methods indicating a low risk. His brother, Joel Turnbull, also participated in the study and found out he had an aggressive prostate tumor. "It's incredible to think that because of this study two lives have now been saved in my family," Dheeresh said.

Toward Wider Implementation

Experts believe the saliva test could be used as an additional screening tool, particularly for men over 50 or those with a family history of prostate cancer. While routine PSA testing is not currently available on the NHS, men can request a test from their GP. The new saliva test could provide a more accurate and less invasive way to assess risk, potentially leading to earlier detection and more effective treatment. Health Secretary Wes Streeting has signaled support for a national prostate cancer screening program, and this new saliva test could be a key component in implementing such a rollout.

The development of a more accurate and accessible screening method offers hope for improving outcomes and reducing the burden of this prevalent disease.