These tumors are more likely to be organ confined at the time of surgery.
ANAHEIM, Calif.—Prostate cancers found as a result of PSA screening are less likely to exhibit extracapsular extension and positive surgical margins after radical prostatectomy than tumors found in a non-screened population, despite similar PSA levels, data show.
In addition, a separate study by researchers in Sweden suggests PSA screening should begin at age 44 instead of age 50, the current recommendation in the United States.
Researchers in Tyrol, Austria, evaluated 997 patients from Innsbruck undergoing radical prostatectomy between February 1999 and March 2006. Within that group, 806 had participated in the PSA Screening Tyrol Prostate Cancer Demonstration Project, and 191 were from a non-screening group.
The mean age of both groups was 60 years. The investigators analyzed preoperative total PSA levels, age, pathological characteristics, and prostate volume, finding that screen-detected cancers were significantly more likely to be organ confined at the time of surgery.
“This is the first study to look at this,” lead investigator Alexandre Pelzer, MD, assistant professor of urology at the Medical University of Innsbruck. “The principal goal is to decrease mortality, and we do decrease mortality by about 50% in Tyrol compared to the rest of Austria, where there is no organized screening.”
For the past several years, the Tyrol PSA Screening Project has produced data supporting the use of PSA screening in men age 50 and older. The new data show that screening results in patients being picked up with lower grade disease and lower risk of having positive margins.
In a separate study presented at the meeting, researchers in Malmö, Sweden, analyzed PSA serum samples on 21,277 men aged 33-50 years. In this part of Sweden, there are no current recommendations for prostate cancer screening and the rate of PSA testing is very low. A total of 498 men had been diagnosed with prostate cancer by December 31, 1999, and 161 were defined as metastatic and/or clinical stage T3 or higher at the time of diagnosis. The researchers selected three controls for each case matched by age and date of blood sample.
The median delay from baseline PSA screening to diagnosis was 17 years. Plasma levels of all PSA forms were strongly associated with case status. Even a small elevation in total PSA levels markedly increased risk. The risk of advanced prostate cancer by age 75 was 2% for men with a total PSA level of 0.5 ng/mL.
There was a direct increase in risk with each higher level. The risk increased to 3% for men with a total PSA level of 0.75 ng/mL; 4% for a level of total PSA of 1.0 ng/mL; 7% for men with a total PSA of 1.5 ng/mL; and 12% risk (three times the population mean) for men with a total PSA of 2.0 ng/mL at age 44-50.
The researchers concluded that screening and chemoprevention trial efforts could be risk-stratified if men were screened between the ages of 44 and 50. Study investigator Hans Lilja, MD, PhD, who presented the findings here at the American Urological Association annual meeting, said that this approach could lead to more frequent monitoring of those found at baseline to have elevated risk.
Ultimately, this could help reduce prostate cancer morbidity and mortality rates. In this study, risk was highly concentrated, with 60% of the advanced cancers occurring in men in the top 20% of PSA levels in this population of men aged 50 years, and younger at the time when blood was drawn at baseline.