Men with a moderately elevated prostate specific antigen level should have the finding confirmed with a repeat test before biopsy is done because levels commonly fluctuate somewhat above and below the normal range, according to an article in the May 28th issue of the Journal of the American Medical Association.
James Eastham, MD, and his American colleagues studied almost 1000 men over a 4-year period, all of whom had 5 consecutive tests done for prostate specific antigen level. Up to 1 in 3 men had an elevated antigen level. However, subsequent testing of those men a year or more later showed that the level in half of the group had returned to normal. The authors concluded that an immediate biopsy in those men may well have been unnecessary.

"A single, elevated prostate specific antigen level does not automatically warrant a prostate biopsy," said Eastham, the study's lead author. "We recommend having the findings confirmed by repeating the [antigen] test after waiting at least 6 weeks. Even if the repeat test shows an elevated level, prostate cancer will only be discovered in about one quarter of men who undergo biopsy."

The retrospective study involved a population of 972 men (median age, 62 years) who had participated in a colon polyp prevention trial. The men were considered typical of the healthy male population at risk for prostate cancer. For the current study, researchers analyzed blood samples that had been taken annually and stored in order to look at natural fluctuations in antigen level.
Men who had 5 consecutive samples available over a 4-year period were included in the current study. Although 21 percent of the group had an elevated prostate specific antigen level (greater than 4.0 ng/mL) at some point during the study, the level subsequently returned to normal spontaneously in nearly one half of that group. The level remained normal for most of those men on later tests.

"These natural variations in prostate specific antigen detract from its use as a screening tool," said Colin Begg, Ph.D., senior author of the study. "A policy of confirming newly elevated prostate specific antigen levels several weeks later may reduce the number of unnecessary procedures as well as the number of men diagnosed with a small, incidental tumor that poses no threat to life or health."

A delay in confirming a diagnosis of prostate cancer will not have an adverse affect on those men who actually have prostate cancer, according to Peter Scardino, MD, another coauthor. "A delay in diagnosis of a few weeks or months is unlikely to alter treatment efficacy," he said.