Aug. 3, 2001 -- To screen or not to screen -- and how often? Those are questions that continue to vex doctors and public health experts seeking to prevent prostate cancer.
The American Cancer Society and the American Urological Association have both recommended annual PSA (prostate specific antigen) screening -- a simple blood test -- of men over 50. But a new study by researchers in The Netherlands suggests that screening every four years might be sufficient to detect serious cancer, while saving considerable amounts of money on unnecessary tests.
The study is seriously questioned by at least one American urologist who says screening at four-year intervals will miss many serious cancers. "The study is full of flaws," says William Catalona, MD, professor of urology at Washington University School of Medicine in St. Louis, Mo. "I don't think they come close to proving that an interval of four years is safe."
Study author Robert Hoedemaeker, MD, says the costs are not worth the minimal amount of serious cancer that is detected by annual screening. "Periodic screening with a one-year interval is very costly and someone has to pay for these healthcare costs," he tells WebMD. "We have shown that a four-year interval is acceptable and safe, and that a one-year interval is too often."
He is with Erasmus University, in Rotterdam, the Netherlands.
In the study -- published in the Aug. 1 edition of the Journal of the National Cancer Institute -- 4,133 men received initial PSA screening, and 2,385 of them were screened a second time four years later. Results showed that most of the serious cancers were detected at the first screen: the cancers that were detected at the first screening were larger and had higher Gleason scores (a measure of tumor aggressiveness) than those detected at the second screen. And a high PSA score at the first screen was much more likely to be followed by a positive biopsy of the prostate than at the second screen, according to the researchers.
In other words, Hoedemaeker says, most of the serious cancer is detected in the first screening, and not much is missed by waiting four years to screen again.
No way, says Catalona.
For one thing, a substantial number of men who have a high PSA at first screening but then receive a negative biopsy actually will have cancer that may be quite aggressive. Waiting another four years to screen them could be dangerous, he says.
And even PSA scores themselves can change dramatically just within a year. Catalona cites the example of New York Yankees manager and prostate cancer survivor Joe Torre: he had a PSA score of 2.6 one year, but the next year it was 4.6.
Finally, Catalona says the researchers' determination of what constituted a "serious" cancer did not include whether the cancer had spread beyond the prostate. Screening every year allows detection and treatment of the vast majority of cancers before they spread to other organs.
"We have found that at the first screen you tend to pick up about 70% of cancers that are organ-confined," he says. "But if you screen every year, after a while you get it up to over 80%."