Sept. 19, 2000 -- As prostate cancer is the second most common type of cancer in men in the U.S., screening tests to detect it early have been a major focus of cancer prevention. But the debate rages on over the best strategy for screening and its ultimate benefits.
The prostate is a walnut-sized male sex gland located between the bladder and rectum, and is easily felt during a rectal examination. Unfortunately, by the time examination picks up prostate enlargement or irregular growths, cancer may be in its later stages.
A blood test called prostate-specific antigen (PSA) helps detect prostate cancer earlier. In 1992, the American Cancer Society recommended that PSA testing be done every year starting at age 50, or at age 40 in blacks, as they are at higher risk of getting the disease and of dying from it.
But research from Johns Hopkins University in Baltimore, Md., published in the Sept. 20 issue of the Journal of the American Medical Association, may suggest a better strategy, one that starts earlier, but then tests less often.
"Testing yearly beginning at age 50 uses more resources and prevents fewer prostate cancer deaths than a strategy of testing at ages 40, 45, and then every other year beginning at age 50," study co-author H. Ballentine Carter, MD, tells WebMD.
"Thus, some physicians and their patients may choose to begin PSA testing before age 50," says Carter, a professor of urology and oncology at Johns Hopkins University.
Carter's group fed statistics on prostate cancer, including the effects of treatment on outcome, into a computer model to predict the results from different PSA testing strategies.
"How often should physicians perform PSA screening? I agree that the answer is less often," says William P. Moran, MD, MS, who reviewed the study for WebMD.
"Despite its rapid adoption in screening for prostate cancer ... PSA has not been shown to reduce [deaths] or improve quality of life," says Moran, an associate professor of medicine at Wake Forest University School of Medicine in Winston-Salem, N.C.
Part of the controversy surrounding PSA testing is that it may cause needless biopsies, or surgical removal of part of the prostate tissue to make the diagnosis. Especially in elderly men, prostate cancer may be of lesser importance than their other health problems. They are less likely to respond well to treatment and more likely to die of unrelated causes. So early detection of prostate cancer in this group may be of limited benefit.
Still, "it may turn out that the best strategy for the individual patient may not be that which minimizes the use of resources," William J. Catalona, MD, tells WebMD. "It may be better to perform a few more screenings and biopsies to prevent more prostate cancer deaths." Catalona, who was not involved in the study, is a professor of urological surgery at Washington University School of Medicine in St. Louis.
Carter says future studies should address whether earlier diagnosis and treatment can actually improve cure rates for prostate cancer.
Carter and Catalona explain that these findings are only accurate to the extent that the computer model accurately represents the typical course of prostate cancer and its long-term response to treatment.
This study did not address the effect of rectal examination or other screening tests on decreasing prostate cancer deaths, optimal screening strategies in blacks, or side effects of treatment.
Individual decisions on how best to screen for prostate cancer, and how often, should be discussed with your doctor, taking into account your own health situation and your own feelings about aggressive management.