Monday, April 4, 2016

Another Diagnostic Tool

The ongoing debate about PSA and PCa in men continues and the search for an improved diagnostic tool has also progressed. Three years ago we wrote a piece on Oncosomes. Recently in a JAMA Oncology Editorial the authors speak of this technique as if it has now been accepted. The Editorial concludes:

Currently, we do not have a single population-based screening test to supplant PSA-based  stewardship in screening for prostate cancer. However, McKiernan and colleagues have introduced a novel urinary gene expression signature that may be the least invasive of available options by not  requiring a digital rectal examination or phlebotomy as a reflex test in men for whom PSA testing  raises the suspicion of prostate cancer.7 In the near future, a panel of markers associated with the risk of high-grade prostate cancer may decrease the rate of overdiagnosis and overtreatment of  prostate cancer that prompted the US Preventive Services Task Force to issue a grade D recommendation for prostate cancer screening.

The paper by McKiernan et al presents a several year definitive study of this oncosome approach. They conclude:

This urine exosome gene expression assay is a noninvasive, urinary 3-gene expression assay that discriminates high-grade (≥ GS7) from low-grade (GS6) cancer and benign disease. In this study, the urine exosome gene expression assay was associated with improved identification of patients with higher-grade prostate cancer among men with elevated PSA levels and could reduce the total number of unnecessary biopsies.

 The question is; how effective will this be in saving lives at the cost of saving on unnecessary prostate biopsies. We have commented on this conundrum lately. It is a complex issue. In light of the "Moonshot" approach of the Vice President, this is still somewhat in the pre Galileo period of celestial dynamics.