A potential a new blood test for prostate cancer is 94% accurate and could avoid unnecessary and invasive biopsies by examining the levels of five chromosome conformations.
Researchers from Imperial College London, the University of East Anglia (UEA) and technology company Oxford Dynamics, found that by combining a new blood test with standard testing practice, more cases could be correctly identified.
The existing prostate-specific antigen (PSA) test is widely used in the NHS. However, the researchers claim that the test suffers from significant accuracy problems. Professor Dmitry Pshezhetskiy, a researcher from UEA, said that ‘only about a quarter’ of people who have a prostate biopsy following a PSA test are found to have prostate cancer.
This results in ‘unnecessary prostate biopsies in men with benign disease and false reassurance in some men with cancer’ according to the paper published in the journal Cancers.
The PSA test looks at the levels of prostate specific antigens in the blood of patients. Levels higher than 3ng/ml result in a follow up targeted needle biopsy.
However, this test only has a sensitivity (a measure of how often a positive result is correctly identified) of 59% and a specificity (how often a negative result is correctly identified) of 89%.
The researchers claim that this is due to the fact that PSA may be present even in asymptomatic cases and may be present at lower rates due when more aggressive tumours are present.
The researchers developed an epigenetic chromosomal test which detects cancer-specific chromosome conformations in the blood of patients.
Using ‘EpiSwitch’ technology the researchers were able to identify five ‘three dimensional chromatin conformations’ associated with the presence of prostate cancer cells.
These epigenetic modifications involve the ‘presence of stable chromatin loops in the loci encoding for of DAPK1, HSD3B2, SRD5A3, MMP1, and miRNA98’.
By combining a test for these biomarkers in combination with the PSA test the researchers developed a screening method which they say would be ‘cost-effective, scalable, and easily accessed in most diagnostic facilities,’ as well as only requiring a small blood sample.
In a pilot study of 147 patients, use of the chromosomal test in combination with the PSA test was found to be 94% accurate; significantly improving detection accuracy.
If the test was adopted widely, the researchers hope that improving accuracy of screening would reduce the number of expensive, time-consuming, and invasive prostate biopsies required in detecting the cancer.
Prostate cancer is the most commonly occurring cancers among men, affecting one in six men throughout their lifetimes. Just under 50,000 men are diagnosed with prostate cancer every year in the UK.
Additionally, because the symptoms are not specific, the cancer is often diagnosed late, with an estimated 12,000 deaths in the UK annually. Symptoms of prostate cancer include difficulty urinating, or blood in the urine.
Professor Pshezhetskiy said that, in the context of screening an at risk population, the newly developed test ‘yields a rapid and minimally invasive prostate cancer diagnosis with impressive performance. This suggests a real benefit for both diagnostic and screening purposes.’
Dr Jon Burrows, chief executive officer at Oxford Biodynamics, said: ‘There is a clear need in everyday clinical practice for a highly accurate blood test that can screen men for prostate cancer and accurately identify those at risk, while sparing those who up to now would be subject to unnecessary, expensive and invasive procedures.’