Antigen Levels Show Prostate Cancer’s Aggressiveness

The level of prostate-specific antigen (PSA) in serum is often used to diagnose prostate cancer. Some patients with high PSA levels undergo invasive biopsies or surgery, which can cause side effects like incontinence and impotence. Some prostate cancers are slow to progress, and studies have shown that some patients do better if they watch and wait instead of having surgery. Michael J. Ahrens of the biotech firm Ohmx Corp. and coworkers, including chemist Thomas J. Meade of Northwestern University, have now tested what could turn out to be an improved diagnostic procedure, and initial results are promising (Prostate 2013, DOI: 10.1002/pros.22714). The researchers propose that PSA enzymatic activity, instead of PSA concentration, be measured to assess prostate cancer’s aggressiveness. Their study of surgically treated patients finds that higher levels of PSA activity correspond with less aggressive types of prostate cancers. “Our results suggest that many—22% in our study population—of the diagnosed patients with nonaggressive prostate cancer could have averted or delayed radical prostatectomy,” the researchers note. Ohmx is continuing validation studies and developing a commercial test, which they have trademarked PPA (PSA Peptidase Activity).