The PSA test: What is PSA anyway?
The U.S. Preventive Services Task Force has released a draft recommendation that PSA tests no longer be used for routine screens for prostate cancer.
What is PSA anyway?
Prostate-specific antigen is an enzyme of a type called a protease; it cuts up other proteins. Scientists believe it helps liquefy semen, and it may help sperm find its way to an egg by digesting the mucus covering the cervix.
When cancers develop in the prostate gland, levels of PSA can start to climb in the blood. (One of the problems with the use of PSA a test is that noncancerous prostate growths — such as benign prostatic hyperplasia — can also cause this to happen.)
It’s common with cancers for certain proteins to be overproduced by the body. The cancer that afflicted Steve Jobs, for example, was a rare cancer of the pancreas called an islet cell neuroendocrine tumor. Depending on which kind of islet cell turned rogue to cause the cancer, the body can start overproducing insulin, glucagon or gastrin, leading to different early symptoms.
The gene that carries the coding instructions for PSA is part of a family of at least 15 genes that make similar protein-cutting enzymes, and researchers are trying to figure out what potential these could have as markers for other cancers — as well as what role they may have in contributing to cancers and other diseases.
When all is going right in the body, this class of proteins appears to be involved in a broad array of functions, such as regulating blood pressure, skin health, tissue remodeling and inflammation. It’s a busy enough field of study that it warrants its own meeting: Scientists gathered last month in Rhodes in Greece to discuss the latest developments.
PSA is not only produced by the prostate, scientists now know. It’s also present in fluid that can be aspirated from nipples, in breast cysts, in mother’s milk and amniotic fluid. Scientists suspect it has functions in the breast, and they think it may also have some role in fetal development.
You can read more about PSA here and, if you want, positively drown yourself in technical knowledge about the family that PSA belongs to — the kallikreins — right here.
