PSA Test

This study suggested that annual PSA screening tests for prostate cancer might not be necessary for many men. Men whose initial tests show very low PSA levels may safely choose less frequent screening, once every five years in some cases. Some organizations currently recommend that a PSA test be offered annually to men age 50 and older. The test detects blood levels of prostate-specific antigen. Higher than normal levels may indicate pros-tate cancer.

This study is part of the National Cancer InstituteÆs nationwide PLCO (pros-tate, lung, colorectal, ovarian) cancer screening trial. The PLCO trial is still ongoing. In this particular analysis, researchers followed 27,863 men ages 55-74 for five years. Of those men, 90% had initial PSA levels that were considered normal (less than 4 ng/ml). Based on the results, they predicted how many men would have PSA levels rising above normal in five years.

The researchers found that most men (98.6%) with extremely low initial PSA levels (under 1 ng/ml) would continue to have normal PSA tests over the next four years. Most men (98.8%) with PSA levels of 1-2 ng/ml would also have a normal PSA test the following year.

One question of the PLCO trial is if PSA screening improves survival in men with prostate cancer, and that question has not been answered yet. These are interim results and do not yet indicate if PSA screening itself improves survival. (Abstract #4)

What does this mean for patients?

The researchers estimate that if men with a PSA below 1 ng/ml are screened once every five years and those with PSA levels of 1-2 ng/ml are screened every two years, only 2.6% of men would miss an earlier potentially positive test.

The researchers recommend that men with PSA levels of 2-4 ng/ml, should be followed more closely. They predict that 24% of this groupÆs PSA levels will become elevated within one year, and 83% rise within four years.

"We found that the vast majority of men whose initial PSA levels are very low do not need to worry that they would skyrocket within one year," said E. David Crawford, MD, Senior Associate Director at the University of ColoradoÆs Health Sciences Center.