If you have prostate cancer, your best bet is to find out early so it can be treated before it spreads, right? Not necessarily, say a number of cancer researchers. Since the late 1980s, US doctors have been using the prostate-specific antigen (PSA) test to detect early prostate cancer in men without symptoms of the disease. But the PSA test merely measures the levels of prostate-specific antigen in the blood, which may or may not be related to the risk of dying from prostate cancer.
The October 5, 2002 issue of
British Medical Journal
) reports the latest study to refute arguments for widespread screening with PSA tests. According to this study, men screened regularly with PSA tests are no less likely to die from the disease than men who don’t undergo PSA screening tests. However, men who have the PSA test are more likely to have a prostate biopsy (removal of a sample of prostate tissue for testing).
About the Study
US researchers studied the Medicare insurance claims of 94,900 men in the Seattle-Puget Sound area of Washington State and 120,621 men in Connecticut. All men were between the ages of 65 and 79 and free of prostate cancer when they entered the study between January 1, 1987 and December 31, 1990. From 1987 to 1990, PSA testing to screen for prostate cancer was very common in the Seattle-Puget Sound area, but much less common in Connecticut. Men who underwent PSA tests or biopsies after diagnosis of prostate cancer were excluded from this study, because their tests were not performed to screen for asymptomatic disease.
The researchers reviewed Medicare claims data for PSA tests, prostate biopsies, prostate removal surgeries, and radiation treatments for prostate cancer. In addition, they used the National Cancer Institute’s cancer registry to identify prostate cancer diagnoses and deaths from prostate cancer. They followed the men through 1997 to see who died of prostate cancer.
Researchers compared the number of PSA tests and other prostate procedures among the Seattle-Puget Sound men with the Connecticut men. In addition, they compared the death rates from prostate cancer between the two groups.
Not surprisingly, between 1987 and 1990, men in Seattle-Puget Sound were five times more likely to have a PSA test and two times more likely to have a prostate biopsy than men in Connecticut. Similarly, Seattle-Puget Sound men were six times more likely to have surgery to remove the prostate and two times more likely to have radiation treatment than the Connecticut men. However, there was no difference in death rates from prostate cancer between the two groups over the 11-year study period.
These numbers have been adjusted to account for age, race, and area of residence—all factors that may affect prostate cancer risk.
Although these results suggest that regular screening with PSA tests doesn’t result in a lower death rate from prostate cancer, this study has its limitations. First, the study only included men aged 65 and older. It’s possible that screening with PSA tests would benefit men younger than 65. Second, the study period of 11 years may not have been long enough to identify a difference in prostate cancer deaths. This is because the majority of prostate cancers are believed to grow very slowly. Third, the cause of death listed on a death certificate may not always include all diseases or factors contributing to death. Finally, it’s possible that the Seattle-Puget Sound men differed from the Connecticut men in some way that affects their risk of prostate cancer (such as dietary habits), but that the researchers didn’t account this.
How Does This Affect You?
Will regular PSA tests reduce your risk of dying from prostate cancer? Not necessarily. PSA testing can detect prostate cancer in its early stages, but there is no conclusive evidence that treating prostate cancer early results in improved survival. This study adds to other evidence that widespread PSA testing to screen for asymptomatic prostate cancer does not necessarily lower death rates from the disease.
Although screening for disease and treating it early may save lives, it’s important to consider the potential negative effects of treatment and the likelihood that treatment will improve survival. Prostate removal surgery carries the risk of erectile dysfunction (impotence) and urinary leakage. And in the end, some cancers never spread beyond the prostate to kill the patient before he dies of some other cause. For these reasons, widespread screening for prostate cancer runs the risk of exposing men to tests and treatments that won’t be beneficial and that may reduce quality of life. The bottom line? Talk with your doctor about the risks and potential benefits of PSA testing before undergoing the test.
Lu-Yao G, Albertsen PC, Stanford JL, et al. Natural experiment examining impact of aggressive screening and treatment on prostate cancer mortality in two fixed cohorts from Seattle area and Connecticut.
Chapple A, Ziebland S, Shepperd S, et al. Why men with prostate cancer want wider access to prostate specific antigen testing: qualitative study.
Thornton H, Dixon-Woods M. Prostate specific antigen testing for prostate cancer.
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