One PSA Test in Midlife Can Predict Cancer in Older Age

By John Schieszer

ANAHEIM, Calif—Although current US guidelines do not call for it, you may want to consider assessing the long-term risk for prostate cancer in your male patients in midlife (ages 44-50 years) using a prostate-specific antigen (PSA) test, according to new findings presented at the American Urological Association annual meeting. These data show that total PSA levels at an early age are a strong predictor of subsequent advanced prostate cancer.

"These are significant findings and add to the debate about how to revise how we screen for prostate cancer. Maybe we should screen a man in his 40s," said Christopher Amling, MD, professor of urology at the University of Alabama-Birmingham, commenting on these findings during the meeting.

In the study, PSA serum sampleswere obtained from 21,277 men (aged 33-50 years) between 1974 and 1986in Malmo, Sweden, a country thatdoes not currently have recommendations for prostate cancer screening,and where the rate of PSA testing is very low.

Of these men, 498 were subsequently diagnosed with prostate cancer by January 1, 2000; 161 of these cases were defined as metastatic or stage T3 cancer at the time of diagnosis. Conditional logistic regression analysis was used to determine any associations between PSA levels and each case status.

The median delay from blood draw at baseline (used to measure PSA) to diagnosis of prostate cancer was 17 years. Plasma levels of all PSA forms were found to be strongly associated with case status. Even a small elevation in total PSA levels markedly increased the risk of subsequent prostate cancer.

A direct correlation was found between prostate cancer risk at an older age and the PSA level at the first testing. The probability of being diagnosed with advanced prostate cancer byage 75 was:

• 2% for men with a total PSA of 0.5 ng/mL
• 3% for a total PSA of 0.75 ng/mL
• 4% for a total PSA of 1.0 ng/mL
• 7% for a total PSA of 1.5 ng/mL
• 12% for a total PSA of 2 ng/mL.

Hans Lilja,MD,PhD

"Currently, PSA testing is highly controversial. If you look across Europe and Scandinavia, there are several national guidelines that do not recommend use of the PSA test for population-based screening," said coinvestigator Hans Lilja, MD, PhD, attending research clinical chemist at Memorial Sloan-Kettering Cancer Center, New York City. "However, a PSA test taken very early once in life, before age 50, has undoubtedly a high capacity to predict future risk for cancer with an unquestionable significance."

Dr Lilja said that screening and chemoprevention efforts could be risk stratified if men were screened between the ages of 44 and 50 years. This approach could lead to more frequent monitoring of those at increased risk, helping reduce prostate cancer morbidity and mortality rates.

"This suggests that instead of waiting until a man is 50 years old, wecould identify some of these men in their 40s with a PSA that is considered normal, yet predictive of eventual development of advanced disease," said Dr Amling.

Dr Lilja added that these data need to be validated in independent study cohorts. If validated in men from different regions or countries, then PSA screening guidelines may need to be revised, he said.

Current US guidelines call for a baseline measurement of PSA at age 50 for men without known risk factors. However, Dr Lilja said that recommending a measurement of PSA for men starting at age 44 to 50 years, and then focusing subsequent screening on those at highest risk, may help lower prostate cancer death rates.