A recent study suggests that a man's PSA level measured once when he is in his mid-40s to age 50 can predict whether he will develop prostate cancer up to 25 years later.
The prostate-specific antigen (PSA) test measures an enzyme produced almost exclusively by the glandular cells of the prostate. It is secreted during ejaculation into the prostatic ducts that empty into the urethra. PSA liquefies semen after ejaculation, promoting the release of sperm.
Normally, only very small amounts of PSA are present in the blood. But an abnormality of the prostate can disrupt the normal architecture of the gland and create an opening for PSA to pass into the bloodstream. Thus, high blood levels of PSA can indicate prostate problems, including cancer.
A blood test to measure levels of PSA was first approved by the U.S. Food and Drug Administration (FDA) in 1986 as a way to determine whether prostate cancer had been treated successfully and to monitor for its recurrence. Today, however, PSA tests are FDA approved for prostate cancer detection and are widely used to screen men for the disease.
-
Now a article published in the the Journal of Clinical Oncology (Volume 25, page 431) suggests that a man's PSA level in middle age may be predictive of prostate cancer years later.
The researchers examined the records and stored blood samples of more than 21,000 men who were age 50 or younger between 1974 and 1986. An average of 18 years later, nearly 500 of the men had developed prostate cancer. The investigators compared PSA data from 462 of these men with data from a group of 1,222 similar men who had not developed prostate cancer. They also looked at other potential prostate cancer risk factors, such as family history, diet, and exercise.
A man's total PSA level in middle age was the strongest predictor of whether he would develop prostate cancer. Using a PSA level of 0.5 ng/mL or lower for comparison, the researchers found that men whose PSA level was 0.51–1.0 ng/mL were 2.5 times more likely to develop prostate cancer. For those with PSA levels between 2 and 3 ng/mL (often considered to be in the "normal" range), the risk was more than 19 times higher.
Bottom line: The results suggest that PSA measurement in middle age might one day be used to determine which men need more intensive prostate cancer screening and which can be screened less frequently.
