Super-sensitive tests helps predict chances of long-time survival of prostate cancer patients
The study, led by Chad Mirkin, focused on an ultrasensitive prostate-specific antigen (PSA) test that uses nanoparticle-based technology (VeriSens PSA, Nanosphere Inc). The test, as described by the authors, is 300 times more sensitive than commercial tests that are currently available and can detect low PSA levels that may indicate that cancer has spread beyond the prostate.
First, researchers obtained blood serum retrospectively from men whose PSA serum samples had been frozen after surgery and whose assays showed an undetectable PSA level based on the conventional test. Then, the serum samples were tested using the ultrasensitive test.
The results of the study revealed that low and nonrising PSA levels meant that the prostate cancer was effectively cured and did not return over a period of at least 10 years. The researchers also reported that a PSA level higher than expected from the periurethral glands based on the new test meant that the disease would recur.
“This test may provide early and more accurate answers,” said co-principal investigator C. Shad Taxton, MD, an assistant professor of urology at the Feinberg School of Medicine and a member of the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. “It detects PSA at levels in the blood that cannot be detected by conventional tests. It may allow physicians to act at the earliest and most sensitive time, which we know will provide the patient with the best chance of long-term survival.”
Results of the study allowed the researchers to assign a PSA level number to a cure for the first time, as well as a number that indicated whether the disease would recur and if the recurrence would be aggressive. According to the authors, these newly identified levels were below what could have been detected with the conventional test.