Prostate specific antigen PSA (Prostate-specific antigen) is a glycoprotein named serinprotease produced exclusively by epithelial cells of the prostate and in small amounts by other glands. This glycoprotein normally increases the mobility of spermatozoa. In the prostatic tissue two specific proteins of the same are produced, one is the prostatic acid phosphatase and the other is the PSA. This protein or rather glycoprotein is the one that is associated with prostate cancer. It is not that it is increased in its formation with the cancer since the epithelial cells of the normal tissues of the prostate and the hypertrophic tissues produce more PSA than the prostatic tissues tumor. In prostate cancer this protein increases its output into the bloodstream through the vessels and lymphatic tissues that pass through the prostate. Methods of Analysis Normally, the analysis is performed by adding to the serum to test a monoclonal antibody (only recognizes this glycoprotein). This antibody will bind only to the recognized PSAs, those remaining free are removed by a wash. A radioactive or enzymatic marker is then applied to measure the amount of this antibody that has been fixed, representing the amount of PSA that exists in the serum tested. There are modifications of this analysis with double sandwich techniques with two monoclonals, or with different markers for detection. The elevation of PSA-free indicates benign prostatic hyperplasia, if the elevation is PSA-conjugated is more indicative of cancer. But the usual measurement detects both the free form and the PSA conjugate. Specific measurements of both are being developed to improve the sensitivity of this analysis. The elevation of PSA may be due to infection or benign prostatic hypertrophy or trauma to the prostate. The most representative to associate the level of PSA and prostate cancer is to observe an elevation of 0.75 ng \/ ml or greater in 1 year. It should also serve to observe the evolution of the treatment of prostate cancer, since if the level rises following a prostatectomy is indicative of persistent malignant tissue or a recurrence of it.