[Prostate-specific antigen (PSA) in women]

Prostate-specific antigen (PSA) is a serine protease with chymotrypsin-like enzymatic activity. In males PSA is produced by the prostatic gland and it is present in prostatic tissue, seminal plasma and male serum. Initially, PSA was believed to be absent from all female tissues and fluids. However PSA has been detected recently in some female tissues (including breast, ovarian and endometrial tissues) and body fluids (serum, milk, amniotic fluid). The presence of PSA in these female tissues seems to be closely associated with steroid hormone regulation, especially androgens and progestins. Estrogen by itself seems to have no effect on PSA regulation, but it can impair androgen induced PSA production. In the tissues and fluids examined PSA is found in two molecular forms: free PSA is the enzymatically active form and in a complexed form bound to protease inhibitors. The data presented suggest that PSA can no longer be regarded as a specific prostatic marker, but as a protein that could be produced by cells bearing steroid hormone receptors under conditions of steroid hormone stimulation. Its biological role is not fully clarified, but PSA may be a candidate growth factor in normal tissues, pregnancy and tumors. At this point, PSA shows promise of being routinely used as a favorable prognostic indicator in female breast cancer.