Measuring PSA Activity May Be a Better Predictor of Prostate Cancer Aggressiveness.

Standing room only; Gasparilla Bay, Placida, Florida; BJ Gabrielsen photo.
Standing room only; Gasparilla Bay, Placida, Florida; BJ Gabrielsen photo.

Research results recently published online in the August 9th issue of The Prostate (Prostate 2013, DOI:10.1002/pros.22714) suggest that measuring the biological enzymatic activity (or lack thereof) of prostate-specific antigen (PSA) could be used as a predictor of prostate cancer (PCa) aggressiveness.  As we know, the level of PSA in serum is often used to determine the necessity of prostate biopsies in the diagnosis of prostate cancer. Much research is on-going to discover tests which can be used to measure the aggressiveness of the cancer while at the same time, minimizing the negative side effects often accompanying prostate biopsies. Such a test could also be useful in determining which cancers could be candidates for active surveillance.  In a study of 778 surgically-treated prostate cancer patients, a research team from Ohmx Corporation and Northwestern University have found that higher levels of PSA’s enzymatic activity (aPSA) correspond with less aggressive types of PCa (and vice versa).  Stated differently, the activity of PSA (aPSA) is inversely proportional to disease stage.  “Patients with the most aggressive PCa have significantly reduced PSA activity compared to those with less aggressive disease.” The researchers note that 22% of the men in their study population, namely the diagnosed patients with non-aggressive prostate cancer, could have averted or delayed radical prostatectomy based on their PSA activity findings. Ohmx Corporation is continuing validation studies and developing a commercial test, which they have trademarked PPA (PSA Peptidase Activity). Biochemically, PSA (a protein) is an androgen (hormone) – regulated serine protease enzyme produced by both prostate epithelial and prostate cancer cells. PSA is the major protein found in semen. It is secreted into the prostatic ducts in an inactive form that is then activated biochemically. PSA that enters the circulation is rapidly “bound” although a fraction is inactivated and circulates as “free PSA”. High PSA levels may be predictive of advanced PCa but a large fraction of organ-confined cancers show much lower PSA values that overlap those levels found in men without PCa. Measurement of free versus total PSA can increase specificity for PCa. PSA is also used widely to monitor responses to therapy and is under investigation as a therapeutic target itself. Remember to always discuss these issues with your physician before taking any actions.

But more importantly, whatever your current situation, if you are concerned about prostate cancer either personally or for someone else, remember that God Himself has a message for you. David writes in Psalm 55:22, “Cast your burden upon the Lord and He will sustain you; He will never allow the righteous to be shaken.” In addition, Psalm 34:19 states “many are the afflictions of the righteous; but the Lord delivers him out of them all.”



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