Prostate-specific antigen (PSA)

Prostate-specific antigen, commonly known as PSA, is a glycoprotein produced by the prostate gland which, once secreted into the seminal fluid, causes it to liquefy, increasing sperm motility. The PSA test detects both the free form (about 30%) and the form bound to protease inhibitors (about 70%): in benign prostate disease, the free fraction is higher than in cancer.

PSA testing is related to the size of the prostate gland: the PSA level will be higher in cases of prostatitis, hyperplasia and tumours than in cases of benign hyperplasia.

For this reason, the test is performed for the early diagnosis of prostate cancer in men from the age of 50 (the age is brought forward in the case of a family history) and in the case of a diagnosed tumour, PSA allows monitoring of the clinical stage of the disease and the response to surgical therapy.