PSA is produced by the prostate gland and secreted into the bloodstream. Its levels have long been used by physicians in deciding whether to perform a biopsy to determine if prostate cancer is present. The current threshold for the rate of increase, known as PSA velocity (PSAV) is 0.75 ng/ml/yr, meaning if a man's PSA level rises more than 0.75 in one year, he should consider a biopsy for prostate cancer. In their study of the medical records of nearly 12,000 men, the researchers found that using that PSAV criterion for younger men prevented physicians from detecting possible prostate cancers in those men.

"Finding that PSA velocity is more effective when it is age-adjusted is very important, especially since the oldest of the Baby Boomers turn 60 this year," said Judd W. Moul, M.D., chief of urologic surgery at Duke University Medical Center and lead study author. "In the past few years, 60 or younger has become the peak age for prostate cancer diagnosis. Using PSAV makes it much more likely that we will detect cancers in men of this age."

Moul presented his findings at the 2006 Prostate Cancer Symposium in San Francisco on Feb. 24. The symposium was sponsored by the American Society of Clinical Oncology (ASCO), the American Society for Therapeutic Radiology and Oncology (ASTRO) and the Society of Urologic Oncology (SUO). Funding for the research came through the Duke Prostate Center.

In their analysis, the researchers divided the men into three groups by age, one younger than 60, another ages 60 to 70 and a third older than 70. All men who had one or more PSA values in their medical records were included in the study.

According to their analysis, PSA levels grow more slowly in men under 70, making 0.75 ng/ml/yr an inadequate benchmark when trying to decide whether to proceed with a biopsy in a younger population. Instead, Moul, who is also head of the Duke Prostate Center, said the new optimal age-adjusted threshold for men under 60 is 0.4 ng/ml/yr, and for men between ages 60 and 70, it is 0.6 ng/ml/yr. The current threshold is an accurate predictor for men at or above age 70, he said.

By using the lower thresholds for younger men, researchers identified an additional 9 percent of men under 60 and 3 percent between 60 and 70, who had developed clinically significant prostate cancer. While a lower PSAV guards against any underestimation of prostate cancer, using a lower PSAV could identify some prostate cancers that are not serious and do not necessarily require treatment, noted Moul.

Although prostate cancer is not a more rapidly growing disease in men under 60, identifying more cancer among this age group is an important quality of life issue, Moul said.

"Prostate cancer in young men is not more aggressive, but guys in their 40s and 50s are so young that they have an additional 30 to 40 years to be concerned with this problem," he said. "That's why we recommend an active treatment approach in younger men."

In younger men diagnosed with prostate cancer, Moul said he would generally recommend prostate removal rather than watchful waiting – a tactic often used in older men with the same diagnosis.

In order to have an accurate picture of their PSA levels over time, Moul recommends that men have a baseline test done at age 40, especially if they are at greater risk for developing the disease. Those at greater risk include African-American men and those with a family history of prostate cancer. Those at average risk – Caucasian men and those with no family history – should have a baseline test at 45. If the baseline PSA value is 1.5 ng/ml or less, a man need only be screened every five years. A value above 1.5 ng/ml warrants an annual screening, he said.

There were limitations to the study, noted Moul. All PSA values came from urology patients rather than a sample of the general public. In addition, the study did not count the impact of abnormal digital rectal exams, an additional method used to decide whether a biopsy is necessary, because a negligible number (4.7 percent) of prostate cancers were identified with this test.

In addition to Moul, other co-authors are James M. Hotaling, M.D., Leon Sun, Ph.D., Chuck Scales, M.D., Paul A. Pappas, M.D., Nicholas J. Fitzsimons, M.D., Steve Freedland, M.D., Thomas J. Polascik, M.D., Cary Robertson, M.D., Daniel George, M.D., Craig Donatucci, M.D., Mitchell Anscher, M.D., Philipp Dahm, M.D., Kelly E. Maloney, M.D., David Albala, M.D., Phillip Walther, M.D. All authors are affiliated with Duke University Medical Center Department of Surgery and the Duke Clinical Research Institute.

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