Pro PSA : a "pro cancer" form of PSA?

Pro PSA, the precursor of PSA, is an inactive 244-amino acid protein secreted by prostatic cells. Pro PSA, a distinct molecular form of free PSA in serum, includes native as well as several truncated forms. Clinical studies have recently provided evidence that pro PSA is associated with prostate cancer (PCa). The truncated (-2) pro PSA form accounts for only 6-19% of free PSA in the serum of patients without PCa, but it represents up to 25-95% of free PSA in that of PCa patients. In the PSA range of 2-10 ng/ml, it has been suggested that pro PSA may be useful to detect PCa, and to spare 10-20% of unnecessary prostate biopsies. However, only scant information about the role of pro PSA is available to date, and its real impact on PCa detection remains to be determined. Furthermore, it is questionnable whether pro PSA could be predictive of tumor recurrence of PCa after therapy. Prospective clinical studies with long term followup are needed to clarify this point.