In the prostate cancer field, there has been a push to move beyond PSA testing. With urine tests, it may be possible to avoid biopsies for men with suspected prostate cancer.
With PSA testing to guide decisions, only one in five men is found via biopsy to have a cancer that is sufficiently aggressive (Gleason score of 7 or higher) to warrant treatment right away.
A recently published paper in JAMA Oncology from urologist Martin Sanda and colleagues in the NCI’s Early Detection Research Network shows the potential of urine testing. Sanda’s team reports that two prostate cancer RNA biomarkers detectable in urine (PCA3 and T2:ERG) could be combined to enhance their discriminatory power and reduce unnecessary biopsies by almost half.
The National Cancer Institute’s Cancer Currents blog has an extensive discussion of the JAMA Oncology paper.
The data came from more than 1000 men, divided into “developmental” and “validation” cohorts. An economic analysis [David Howard from RSPH was a co-author] shows that urine testing with the two markers could lower health care costs in comparison with PSA testing alone, especially for men under 65.
In an audio interview with JAMA Oncology, Sanda notes that the PCA3 test is commercially available, but T2:ERG is available in a more limited way and a Medicare fee schedule is not yet set.
These results were already presented in 2015 at the American Urological Association meeting; we mentioned them in a 2015 feature for Winship magazine. Studies presented more recently at AUA have suggested that these two biomarkers, PCA3 and T2:ERG, may be less useful for African American men.
Beyond these two biomarkers, there’s room for improvement, Sanda says. That could come from improved blood tests such as the Prostate Health Index and 4K Score, he and his co-authors write.
Let’s stay with the urine test idea some more: if two urine RNAs are good, then more could be better. Collaborating with Sanda, Carlos Moreno and Kathryn Pellegrini have been evaluating a 24-gene signature (straightforwardly named Sig24), together with GenomeDx Biosciences, a company focused on prostate cancer genomics.
In a recent paper in BJU International, they look at Sig24’s usefulness in the situation when a man has been treated for prostate cancer and may develop metastasis. Higher Sig24 scores were associated with both pathology results (Gleason score) and risk of metastasis. Video on this paper featuring Moreno below.
Sig24 was originally defined in this 2014 Cancer Research paper. Moreno says Sig24 is part of a larger panel of genes being tested for the pre-biopsy urine situation.
This spring, Pellegrini, Moreno and Sanda also published this paper in Prostate showing that extracellular vesicles (tiny membrane bubbles secreted by cells into the urine) are a better source for prostate cancer RNA than stray cells.