A more sophisticated prostate cancer blood test, known as Stockholm3, is gaining attention for its ability to more accurately identify aggressive forms of the disease compared to the standard PSA test used by the NHS. This development comes amid controversy over new NHS guidelines that limit free PSA testing for asymptomatic men over 50, a decision critics argue could lead to more late-stage diagnoses.
The Stockholm3 test, developed in Sweden and available privately in the UK for approximately £395, analyzes not only PSA levels but also four other protein markers and 101 genetic markers. These data, combined with a patient's age and family history, are fed into an algorithm to generate a risk score for aggressive prostate cancer. A 'green' score indicates a low risk, suggesting re-testing in six years, while a 'red' score signals a higher risk, prompting further investigation such as an MRI scan or biopsy.
This advanced approach aims to address the limitations of the PSA test, which can struggle to differentiate between aggressive cancers requiring treatment and slow-growing tumors that may never cause harm. Relying solely on PSA can lead to over-diagnosis and overtreatment, with potential side effects including incontinence and impotence.
Tim Dudderidge, a consultant urological surgeon at University Hospital Southampton, highlighted that the Stockholm3 test appears powerful in identifying serious cases and reassuring men with less significant issues. "It seems quite powerful at identifying bad cases – where there’s a high risk of an aggressive cancer – and at reassuring men who don’t have a significant problem," Dudderidge stated.
A study involving over 12,000 men, published in the Annals of Internal Medicine, compared the Stockholm3 test with the PSA test. The research found that Stockholm3 was more sensitive in detecting aggressive prostate cancer, with a 90% success rate compared to 74% for the PSA test.
Further research is underway as part of the large-scale TRANSFORM trial, which is evaluating various screening methods for the NHS, including fast MRI, genetic screening, and PSA tests, with blood samples also analyzed using Stockholm3. This trial, which began recruiting 16,000 men aged 45 to 74, aims to inform the future of prostate cancer screening, a program that was previously rejected in May partly due to the PSA test's perceived unreliability.
Professor Rakesh Heer, a consultant urologist and investigator on the TRANSFORM trial, noted that the PSA test's inability to distinguish between problematic and non-problematic cancers can lead to unnecessary worry and interventions. He added that tests like Stockholm3 are seen as more effective in mitigating over-diagnosis and over-treatment.
Dr. Martin Scurr, a GP columnist, has recommended Stockholm3 to his private patients, stating it provides a better assessment than the PSA test, particularly for individuals with concerns about their risk, even if they are told they are too young for standard testing. He advises that paying for the Stockholm3 test could be worthwhile for those with significant anxiety regarding their prostate cancer risk.