At Northwestern University researchers have been testing a nanoparticle technology to predict the recurrence of prostate cancer. The underlying technology was developed at Northwestern, and is now being moved toward commercialization by Nanosphere out of Northbrook, Illinois. The latest results, just presented at the American Urological Association 2010 Annual Meeting, show a PSA sensitivity 300 times greater than that of currently available tests.
More about the technology and findings from a Northwestern announcement:
PSA is a protein normally secreted out of the prostate cells into the semen in high concentrations. Usually, very little diffuses into the blood stream, and the normal PSA value for men without prostate disease is less than 2 nanograms per milliliter. When the prostate gland has a disease process, such as inflammation, benign enlargement, or cancer, the barriers to PSA diffusion into the blood stream are breached, and PSA levels rise. In a man who has his cancerous prostate removed, there should be no PSA in the blood except for a minute amount produced by the periurethral glands. However, any PSA produced by cancer recurrence ends up in the blood stream and can be detected earlier with the more sensitive nanotechnology PSA assay.
For the new study, researchers obtained blood serum retrospectively from men whose PSA serum samples had been frozen after surgery and whose assays (blood analysis) showed an undetectable PSA level based on the conventional test. Northwestern researchers then tested those serum samples using the more sensitive nanotechnology-based test. They wanted to see if they could detect PSA at levels below the limit of the conventional test, and if those results could predict the cancer outcome for those patients, who were followed for up to 10 years.
Using the new test, Thaxton [C. Shad Thaxton, assistant professor of urology] and colleagues found that the low and non-rising PSA levels (presumably produced by the normal periurethral glands) of patients meant that the prostate cancer was effectively cured and did not return over a period of at least 10 years. Scientists also found a PSA level higher than that expected from the periurethral glands based on the new test meant the patients would have their disease recur.
As result of the study, researchers were able to assign a PSA level number to a cure for the first time, as well as a number that indicated the disease would recur and if it would recur aggressively. These newly identified levels were below what could have been detected with the conventional PSA test. The researchers were able to quantify PSA values at less than 0.1 nanograms per milliliter, the clinical limit of detection for commercial assays.