PSA stands for “Prostate Specific Antigen” and it is a blood test used to screen for prostate cancer. You may now be asking what is an antigen? An antigen is a biological term for a substance that stimulates an individual to make antibodies. The prostate is a small gland which is located below the bladder and is found only in men. The prostate’s function is to make seminal fluid that is ejaculated along with sperm during intercourse. The most important thing about PSA is that this protein is unique and is essentially only made by the prostate. No other tissue in the body can make PSA in any significant quantity.
All prostates make PSA but the normal prostate holds onto most of its PSA and lets very little leak into the bloodstream. The PSA blood test measures the small amount that leaks out. Any prostate abnormality allows more of the PSA to enter the blood stream. Prostate cancer causes the most leakage, but prostate infection (prostatitis), inflammation, or even just benign enlargement (which most men experience as they age) can all raise the PSA. Even a rectal exam, or ejaculation can cause a temporary small rise in PSA. A biopsy of the prostate can tell which of these problems exists.
It depends on your age, and your doctor can tell you on each case. If you are forty five years old your PSA should not exceed 2.5, however, if you are seventy eight, it may be as high as 6.5 and still be normal. A PSA value greater than 10 is very suspicious for prostate cancer. Urologists often use a more refined “free-ratio” PSA in cases of borderline abnormalities to increase the accuracy of prostate cancer detection.
Although not all experts agree, the American Cancer Society and the American Urological Association recommend PSA testing every year starting at age 50 (in conjunction with a rectal examination). For patients at higher risk (African-Americans, or family members with prostate cancer) screening should start at age forty.
Prostate cancer generally does not cause symptoms until it has spread. PSA identifies cancer in patients before it can be detected with a rectal exam and before it spreads. Early diagnosis is the key to aggressive treatment.
Just ask your doctor or call Dr. Lander.