Screen for Prostate Cancer at age 40, New Study Say -- Then Cut Frequency of Follow Up Exams

New Model of Outcomes Created with Computer

September 20, 2000. The standard, widely-used approach to screen men for prostate cancer -- annual PSA tests after age 50 -- may be less efficient and cost-effective than one that tests men earlier and less frequently, according to a study in Journal of the American Medical Association.

The study used a computer model to simulate the outcomes of prostate cancer detection under various conditions. The medical programers plugged in different ages at which men might first start regular PSA testing, varied the interval between tests and varied the PSA cutoff level urologists use for recommending a biopsy.

The best overall outcome came from a gameplan of screening men twice before they're 50 -- once at age 40 and again at age 45 -- then following that with every-other-year screening, beginning at age 50. This plan "would substantially reduce the cost we spend on prostate screening," said Hopkins urologist H. Ballentine Carter, M.D., a member of the research team who for several years has urged a plan like this without seeing it fully tested by computer. "It would also prevent more deaths from prostate cancer, compared with existing screening practices," Carter said.

Compared with the standard way of screening, he said, "the model showed you'd do 3,000 fewer PSA tests and 200 fewer biopsies for every 1,000 men screened over a lifetime."

"What we've found doesn't mean the world should change screening practices tomorrow. It is, after all, a computer simulation," Carter adds. "But because this simulation is trustworthy, it's very strong evidence indeed that what we're doing now is probably not the best way."

Mary and Lee -- PSA test and prompt treatment played a part in Lee's full recovery. We reported Ballentine Carter's earlier study, Screen at Age 40, in May 1999.

Under most US guidelines for prostate cancer screening, men get an annual PSA (prostate specific antigen) test after age 50, with a follow-up biopsy if the PSA level is higher than 4 nanograms per milliliter of blood. "There's no science to show that you should start at age 50 and test annually," says Carter. "That strategy was adopted because it seemed reasonable, especially in light of women getting an annual mammogram for breast cancer." But, he adds, "prostate cancer tends to grow and progress more slowly than breast cancer, so yearly screening is probably not necessary."

Some men, though, do have rapidly progressing prostate cancer. The patient-survivor community generally advises men as individuals to be sure of their status before relying on two-yearly tests. Carter's model, which simulated a population of 1 million men followed from age 40, for 40 years, may be statistically solid. But individuals are more than statistics.

Under the ground rules of Carter's model the researchers used real data on the way prostate cancer progresses over the years, results of treatment, who gets the disease, and what PSA tests and biopsies can show. They first produced a basic model of the natural history of unchecked prostate cancer. "That's what you'd get with no screening," says Carter.

Then they modeled different PSA screening strategies. The researchers compared each strategy's outcomes on the basis of number of deaths it would prevent and number of PSA tests and biopsies required.

The researchers began their work because one of Carter's earlier studies showed younger men tend to have a higher cure rate from prostate cancer, probably because their tumors are smaller and more confined. "Screening earlier and detecting the disease at a younger age may decrease the number of deaths from prostate cancer in this country," says Carter.

"We can't translate this yet into universal guidelines. The purpose of this study now is to raise awareness. What needs to take place are confirmatory studies with real patients. But based on this study, some physicians and their patients may choose to begin PSA testing before age 50."

Full text of the study report: Comparative Efficiency of Prostate-Specific Antigen Screening Strategies for Prostate Cancer Detection Journal of the American Medical Association Wed Sep 20, 2000

Researchers from Johns Hopkins, Merck Research labs and the University of North Carolina collaborated on the study. The research was funded by grants from the National Cancer Institute. Other researchers were Kevin S. Ross, now a medical student at Hopkins and formerly with the University of North Carolina, Chapel Hill; Harry A. Guess, with the University of North Carolina and the Merck Research labs in Blue Bell, Pa.; and Jay Pearson, Ph.D., with Hopkins and Merck.

What Happened When the PSA Test Hit the USA?

In the early 1990s use of PSA test spread rapidly, encouraged by the American Cancer Society. By 1997, according to Charles R. Smart MD in an editorial called Prostate cancer facts and fiction, (Journal of Surgical Oncology, December 1997), the PSA cut deaths from prostate cancer. Up to 15% of surgeries may have been done on non-life threatening early disease, Smart says. But lives were being lengthened and saved. There was a 20% increase in the overall prostate-cancer affected survival rate. 1. The observed increase in prostate cancer incidence followed by a decrease, was not an epidemic, but the result of generalized prostate cancer screening in the United States. 2. The increase showed a shift in stage, to mainly early disease in grade 2 (Gleason's 4-6) clinically significant cancers with a decrease in advanced disease. 3. There was an increase in the use of radical prostatectomy, mainly in men 40 to 75 years of age with a 10-year relative survival rate of 100%. It appears that 15% were grade 1 cancers and in the absence of more information may have been clinically unimportant. 4. There was a 20% increase in the overall relative survival rate for prostate cancer. 5. There was a decrease in the incidence of advanced disease followed by a 6.3% decrease in the United States mortality rate for prostate cancer. 6. It appears that an annual PSA blood test and a DRE on all men over 50 years of age followed by appropriate treatment has decreased deaths from prostate cancer.