PSA retesting interval can be individualized

Middle-aged men with an initial prostate specific antigen (PSA) level of less than 1 can safely wait for 3 years before repeating the PSA test, a study suggests, while those with PSA levels greater than 1.5 should probably undergo repeat testing every year.

It's currently common practice for middle-aged men to be screened for Prostate cancer with the PSA test annually. The current study findings, say researchers, hint that the PSA screening interval can be individualized based on the initial PSA result.

Dr. Gunnar Aus, from Sahlgrens University Hospital in Goteborg, Sweden, and colleagues followed 5855 randomly selected men initially tested at ages 50 to 66 years in 1995 or 1996.

If their PSA value was 3 or higher, they were offered prostate biopsies. Otherwise, the initial test was followed by repeat PSA testing every two years.

A total of 539 men developed Prostate cancer during the roughly 7 years they were followed, the study team reports in the current Archives of Internal Medicine.

The cause of prostate cancer is unknown, although some studies have shown a relationship between high dietary fat intake and increased testosterone levels. When testosterone levels are lowered either by surgical removal of the testicles (castration, orchiectomy) or by medication, prostate cancer can regress. There is no known association with benign prostatic hyperplasia (BPH).
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The risk of prostate cancer varied markedly according to initial PSA values.

There were no cases of the disease diagnosed among men with PSA values less than 0.5. The risk of prostate cancer was 0.9 percent for those with levels between 0.50 and 0.99, 4.7 percent for those with levels between 1.0 and 1.49, and 12.3 percent for those with levels of 1.5 to 1.99. The risk of prostate cancer rose steadily thereafter to a 76.8 percent risk among those with PSA levels of 10 or higher.

During the first 3 years after the initial PSA test, there were no cases among men with a first-time PSA level of 0.5 to 0.99 and only three cases among those with first-time levels of 1.00 to 1.49.

The authors conclude, based on their findings, that PSA retesting intervals "should be individualized" on the basis of the initial PSA level. The "large group of men" with PSA levels less than 1 can safely be retested every 3 years, they say.

They recommend annual testing for those with PSA levels greater than 1.5.

SOURCE: Archives of Internal Medicine, September 12, 2005.