According to a media release issued on Thursday by IRIS International, the U.S. Food & Drug Administration (FDA) has approved the company’s NADiA® ProsVue™ test as a prognostic marker that can “aid in identifying” men at reduced risk for recurrence of prostate cancer in the first 8 years after a prostatectomy. The company further states that this test “is expected to reduce unnecessary treatment of certain post-prostatectomy men thus reducing the morbidity and costs associated with adjuvant treatment such as radiation therapy.”
Now it is important to appreciate that the approval of a test by the FDA is not necessarily any type of guide to the clinical utility of the test. We have already commented on the data provided to the FDA to justify the approval of this test, and they are data from a retrospective analysis as opposed to a prospective clinical trial. Whether the NADiA ProsVue test has the same level of accuracy when used prospectively in clinical practice is open to some question at the present time.
In theory, this test does have potential utility in assessing the risk of progression of men with prostate cancer following surgery. What is perhaps less clear is exactly whom this test may be most appropriate for. Will it work better in men who were high risk or intermediate risk as compared to low risk or vice versa? It seems unlikely that it is going to be of value to every patient who undergoes surgery — especially if it is shown that the data from prospective use of the test are less impressive than the reported data from the retrospective study.
So … There is no doubt that there is utility for any test that can accurately predict risk that a man who has had surgery for prostate cancer will not have progressive disease within 8 years. Excessive, unnecessary, and costly use of adjuvant and salvage radiation therapy in men who have received first-line surgery should be avoided if possible. On the other hand, what level of confidence can we have in the clinical value of the NADiA ProsVue test based solely on retrospective data analysis? It may take a while to get a really good answer to this question. A well-conducted follow-up registry trial could actually resolve this issue with relative ease.