A SIMPLE at-home spit test could be more accurate than the standard blood test at predicting men who are at a higher risk of developing prostate cancer according to results from a study by The Institute of Cancer Research, London, UK.
Currently, the prostate-specific antigen (PSA) test is used to identify higher-risk men however, it has a false positive rate of 75% and identifies cancers that have such a slow growth rate that most will not become life-threatening. As a result, PSA tests often lead to unnecessary MRI scans, biopsies, and treatment.
The current study aimed to produce a spit test to search for certain genetic variants to identify the more aggressive prostate cancer subtypes with a higher accuracy rate. The cohort consisted of 6,142 European male patients, aged 55–69. Polygenic risk scores (PRS) were calculated based on 130 genetic variations, to identify the top 10% most at-risk individuals, who were subsequently invited for further screening.
Of the 558 men with high PRS, 40% were diagnosed with prostate cancer after additional tests, compared to 25% detected by the PSA test. Notably, 77.8% of these cancers were in men with PSA levels considered normal. The PRS test identified a higher proportion of aggressive cancers, 55.1%, compared to 35.5% by PSA tests. It also proved more accurate than MRI scans, confirming prostate cancer in 63.6% of cases that MRIs missed.
The findings suggest that a PRS-based approach can enhance the detection of clinically significant prostate cancer, identifying a higher proportion of aggressive cancers compared to PSA or MRI-based methods. This study, the first to assess PRS for population screening, indicates that PRS risk stratification may enrich screening programs for detecting prostate cancer that requires treatment, potentially improving early detection and reducing unnecessary procedures.
Further research could compare the PRS saliva test to the PSA blood test and MRI scan, to assess whether those with a low genetic risk may also benefit from this new, alternative screening tool.
Katie Wright, EMJ
Reference
Eeles RA et al. Effect of polygenic risk score for clinically significant prostate cancer in a screening program: The BARCODE 1 study results. Journal of Clinical Oncology. 2024;42(16_suppl):10500.
