The Patrick C. Walsh Prostate Cancer Research Fund
Ultrasensitive PSA Tests: Can They Be Helpful After Surgery?
After radical prostatectomy, a man’s levels of PSA in the blood are supposed to be undetectable, and for most men, this is what happens. If, months or years after surgery, PSA becomes detectable – above 0.1 ng/ml – and there are no other signs that the cancer has returned, this is called “biochemical recurrence.” “Clinical laboratories can confidently measure PSA at those levels,” says Lori Sokoll, Ph.D., the Prostate Cancer Team Scholar. “However, there are ultrasensitive assays that can detect very minute levels of PSA .” Use of these ultrasensitive tests has been controversial. Some scientists have proposed that with these ultrasensitive PSA assays, men who have PSA levels below a specific cutoff point shortly after surgery could have extra reassurance that their cancer is gone for good, and that men with PSA levels above this point might be monitored more closely. Other scientists and doctors believe that these lower levels may just make men anxious when they don’t need to be.
In a preliminary study, Sokoll, with coinvestigators Adam Reese, Daniel Chan, Zhen Zhang, and Alan Partin, used an ultrasensitive assay to measure PSA in men after radical prostatectomy who either had biochemical recurrence or were free of recurrence for at least five years. The ultrasensitive test was able to pick up PSA at higher levels in the recurrence group compared to the men whose cancer did not return. The assay was also able to predict which men would likely be free of biochemical recurrence at five years after surgery.
Next, Sokoll and colleagues are seeking to confirm these results in a larger study and to determine whether another ultrasensitive assay used in the Johns Hopkins Clinical Chemistry Laboratory will have a similar performance. “We hope that this study will help to establish whether there is benefit to using ultrasensitive PSA assays in men after surgery to predict their long-term likelihood of remaining cancer-free.”