Scientists at Queen Mary University of London have developed a new prostate cancer blood test that promises a significant increase in accuracy compared to current blood tests. If verified in larger samples the test should be available to men within three to five years.
Prostate cancer is currently one of the more challenging cancers for doctors to detect. It is often slow growing, and can remain asymptomatic until its later, more aggressive phases. Other than an invasive digital rectal examination, the most common screening tool is a blood test measuring levels of what is called prostate-specific antigen (PSA).
PSA levels are frustratingly inaccurate, with around three quarters of positive results leading to negative and unnecessary biopsies. PSA testing is also relatively controversial, with some clinicians suggesting it can lead to over diagnosis, identifying subjects with tumors that ultimately may be so slow-growing they present no real immediate harm.
“The current prostate cancer test often leads to unnecessary invasive biopsies and over-diagnosis and overtreatment of many men, causing significant harm to patients and a waste of valuable healthcare resources,” explains Yong-Jie Lu, lead researcher on the new study. “There is clearly a need for better selection of patients to undergo the biopsy procedure.”
The new blood test utilizes a technology called Parsortix, which is designed to measure circulating tumor cells (CTCs) in small blood samples. Over 250 subjects were tested using this CTC method, and the researchers found, when combined with the PSA test, aggressive prostate cancer could be effectively detected with around 90 percent accuracy.
Even more importantly, the research found the aggressiveness of the prostate cancer could be measured by examining the number and type of CTCs in a given blood sample. This is perhaps the most significant element of the new test as it may allow doctors to track the progress of a prostate tumor, avoiding unnecessary biopsies or invasive treatments.
“By combining the new CTC analysis with the current PSA test, we were able to detect prostate cancer with the highest level of accuracy ever seen in any biomarker test, which could spare many patients unnecessary biopsies,” says Lu. “This could lead to a paradigm shift in the way we diagnose prostate cancer.”
The researchers suggest it will take three to five years before the test can be rolled out into general use. Broader validation in larger cohorts of men will be necessary before either the FDA in the United States, or the NHS in the UK, can approve the test for clinical application.
The study was published in the Journal of Urology.
Source: Queen Mary University of London
