The researchers found that a new urine test is extremely accurate in detecting aggressive prostate cancer with few false negatives.
The test could have prevented a third of unnecessary prostate cancer biopsies, but failed to detect only a small number of cancers, according to a validation study of more than 1,500 patients.
The MyProstateScore test measures the levels of cancer-specific genes in a patient’s urine. It is based on previous research that found that half of all prostate tumors harbor a certain genetic abnormality in which the TMPRSS2 and ERG genes relocate on a chromosome and fuse – creating a switch to the development of prostate cancer.
One of the best current methods for detecting prostate cancer is a blood test for prostate specific antigen, commonly known as a PSA test. Elevated PSA levels may indicate cancer, but most men with elevated PSA do not have prostate cancer.
To determine which patients have cancer or not, men with an elevated PSA test undergo an invasive procedure called a transrectal biopsy. Prostate biopsies are uncomfortable for patients and have a small risk of complications. MRI scans are also used to detect prostate cancer, but they can also not detect cancerous lesions and have much higher costs and limited availability.
“Our ultimate goal was to determine whether the MyProstateScore test could be a practical and reliable test that could rule out the need for more expensive or invasive tests in men referred for a prostate biopsy,” said study lead author Jeffrey Tosoian, clinical professor at urology in Michigan Medicine.
Not all prostate cancers are of equal concern. Many come later in life and grow so slowly that the best course of action is simply to monitor them. It is patients with these slow-growing or cancer-free cancers who, despite high PSA levels, could be spared from more invasive or expensive procedures with a better test, the researchers say.
The validation study included patients seen at academic health centers and community health settings. Among these 1,525 patients, 338—2% – had cancer detected in the group marked with biopsy grade 2 or higher, meaning that they were severe enough to warrant immediate treatment.
If the MyProstateScore test were available to the study patients, 387 biopsies that found no cancer or slow-growing cancer could have been avoided, the study concluded. In the meantime, the test would have omitted only 10 clinically significant cancers that would have guaranteed immediate treatment.
“The data shows that this direct and secondary testing approach can reduce the use of more expensive and invasive procedures after a PSA test,” says Tosoian.
Additional co-authors of the study, published in Journal of Urology, are from Johns Hopkins University, Fred Hutchinson Cancer Research Institute and the University of Michigan.
The Prostate Cancer Foundation, the National Institutes of Health, A. Alfred Taubman Medical Research Institute and the University of Michigan funded the work.
LynxDX, a startup company at the University of Michigan that Tosoian and colleagues founded and in which they have a stake, is marketing the test.
Source: University of Michigan