New Studies Support PSA Screening, Blacks May Benefit Most

FORT LAUDERDALE, Fla--Although prostate cancer screening remainscontroversial because of lack of a proven effect on disease-specificmortality, Judd Moul, MD, believes that new data regarding prostate-specificantigen (PSA) screening, as well as statistics from the armedforces, strongly support the benefits of screening.

Dr. Moul is a Lieutenant Colonel in the US Army Medical Corpsand director of the Center for Prostate Disease Research, UniformedServices University of the Health Sciences, Bethesda, Md.

In contrast to the reluctance of men in the general populationto undergo rectal examinations, soldiers are conditioned for suchscreening because it is required after age 35, Dr. Moul said atthe second annual conference of Industries' Coalition AgainstCancer .

"History is a great teacher of the obvious," he said,reminding the audience of a study performed 20 years ago at WalterReed Army Hospital. At that time, Walter Reed had a cure ratefor prostate cancer of 50%, compared with only 5% in civilianhospitals. The reason, he believes, is that at that time the militaryrequired an annual exam beginning at age 40, and thus prostatecancer was found early.

Dr. Moul noted that recent findings from the Physician's HealthStudy strongly support PSA screening. The 20,000 study participants,all male physicians, had blood banked in 1982. Thirteen yearslater, the blood was tested for PSA and analyzed according towhether the men did or did not develop prostate cancer duringthat time. The study found that PSA was extraordinarily sensitive(73%) and specific (91%) for the subsequent detection of prostatecancer.

Although a PSA range of 0 to 4 ng/mL is considered normal, thisstudy found that any man who had a PSA greater than 1 ng/mL hada higher relative risk of developing prostate cancer. "Between1 and 1.5, there was a more than twofold risk of future developmentof prostate cancer, and it goes up from there," he said.

Another finding challenged the maxim that men generally die withprostate cancer, not from it. In this study, men who developedprostate cancer had an 80% chance of dying from that cancer.

Dr. Moul also does not consider it a coincidence that after theintroduction of PSA testing in 1988, the percentage of prostatecancer patients presenting with metastatic disease began to fall--fromabout 25% in 1987 to 12.6% in 1992.

Start Screening Earlier in Blacks

Dr. Moul noted that screening may need to start at age 40 in African-Americanmen, rather than 50, which is generally recommended for average-riskindividuals. Blacks have a much higher rate of prostate cancerthan whites, tend to develop it at an earlier age, and are morelikely to die of the disease, he said.

A recent armed forces study of 635 men with newly diagnosed prostatecancer found that across all categories of stage, grade, and age,black men had higher PSA levels than whites. Of those patientswho had a radical prostatectomy, stage for stage, black patientswere found to have a much higher volume of tumor.

"When tumor volume was included in the analysis, PSA wasno longer significant, so higher PSAs in these patient are a surrogateof higher tumor burden," he said. The important questionnow is why these black prostate cancer patients had higher cancervolume. If screening behaviors are to blame, then blacks may benefitgreatly from earlier detection.