Patients who undergo a prostatectomy should theoretically have a stagnant level of PSA, which is a protein secreted from prostate cells into the semen in high concentrations. Generally, concentrations in the blood stream are very low, but when the prostate gland is diseased with cancer, for example, PSA levels in the bloodstream increase. After surgery, there is only a minimal amount of PSA in the bloodstream due to periurethral gland secretion. PSA produced due to cancer recurrence can be detected by this new test.

Being able to detect recurrence early not only can give patients peace of mind, but for those who will experience recurrence, they can undergo treatment early, which could mean better outcomes.


"Clinical data show that early intervention for prostate cancer recurrence results in improved patient outcomes," says Thaxton. "What we hypothesize, using a more sensitive test for PSA, [is that] one can detect recurrence earlier and intervene earlier."

A patient could be tested for PSA levels immediately after a prostatectomy and could see the PSA "wash out of the system," says Mirkin. This can also be seen after radiation treatments.

But it's still unclear how frequently prostate cancer patients would have to undergo the test for the doctor to safely say the cancer is gone. Mirkin estimates that it could be several times a year, and Thaxton guesses that a patient could be deemed "cured" after three years of stagnant PSA levels.

Researchers won't be able to answer these questions until they conduct a prospective study, which is currently in the works, says Thaxton. Instead of looking at serum samples retrospectively like this study, Thaxton explains that a future study would test PSA levels in men who have undergone prostate removal every few months. Both the new and the conventional tests would be used to determine the clinical validity of using a more sensitive test.

But this promising blood test might be able to do more than just detect cancer recurrence, according to the researchers. Because of its sensitivity, the technology can show how effective a therapeutic cancer treatment is early on, by testing PSA levels.

"We can look at how PSA levels are responding to treatment -- radiation, chemotherapy -- and use its ability to look at how low PSA concentrations are, to validate new therapy regimens," explains Mirkin.

Moving forward, the technology could be used to detect other cancer biomarkers that fly under the radar of conventional tests.

"[Right now,] the test is just for recurrence, but think about it from a general cancer type of tool standpoint," says Mirkin. "The assay can be developed for lots of types of different markers, and we can go after a lot of cancers...We can see if we can track those markers unique to tumors and detect very early stages of disease."

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