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Screening for Prostate Cancer: Insufficient Evidence

The USPSTF finds that, although prostate-specific antigen tests can detect early-stage cancer, there is scant evidence that such detection would reduce cancer-specific mortality.

The third U.S. Preventive Services Task Force (USPSTF) has been releasing new and updated guidelines during the past year (guidelines homepage; Journal Watch May 15 2001; Journal Watch Nov 22 2002).

USPSTF 3 concludes each of its guidelines with a recommendation, graded as follows:

A -- The intervention is strongly recommended.

B -- The intervention is recommended.

C -- The USPSTF makes no recommendation for or against the intervention.

D -- The intervention is not routinely recommended.

I -- Evidence is insufficient to recommend for or against the intervention.

Although no major medical organizations recommend universal prostate cancer screening, they clearly vary in their enthusiasm for such screening. The USPSTF, in their last report, recommended against routine screening. Following a review that included studies reported since their last guideline was issued, the task force now finds that there is good evidence that screening can detect early prostate cancer but inconclusive evidence that detection improves health outcomes. They conclude that the evidence is insufficient to recommend for or against routine screening for prostate cancer using prostate-specific antigen (PSA) testing or digital rectal examination (DRE). Recommendation: I

The task force identified 1 randomized trial in which PSA and DRE were compared with no screening; prostate cancer death rates did not differ between men who were, or were not, invited to be screened. Because of the dearth of clinical trials, the task force reviewed observational studies and prostate cancer treatment studies. Of 3 case-control studies, 2 were negative, and 1 suggested that DRE protected against prostate cancer mortality. In 1 randomized trial, researchers compared watchful waiting with radical prostatectomy for clinically detected prostate cancer: Estimated prostate cancer mortality at 8 years was lower in the surgery group (7% vs. 14%), but all-cause mortality did not differ (Journal Watch Sep 20 2002). No other randomized trials were found in which treatment was compared with no treatment for localized prostate cancer.

The USPSTF highlighted the harms of screening: false-positive results, anxiety, biopsies, and complications of treatment for cancers that might never have affected health had they gone undetected. The task force also recommended that clinicians should not order PSA tests without discussing with their patients the potential but uncertain benefits and the possible harms of screening.

Comment: Prostate cancer screening clearly can detect early-stage prostate cancer. But would the detected disease have affected health? Do the benefits of screening outweigh the harms? Only randomized trials will tell us whether screening will improve or worsen rates of morbidity and mortality. Until such data are available, physicians should avoid universal screening, and review possible benefits, risks, and preferences for patients who are interested in screening. At the time of publication, the full text of the original articles was available at http://www.ahrq.gov/clinic/3rduspstf/prostatescr/prostaterr.htm and http://www.ahrq.gov/clinic/3rduspstf/prostatescr/prostatesum.htm free of charge.

— Richard Saitz, MD, MPH

Published in Journal Watch General Medicine January 10, 2003

Citation(s):

U.S. Preventive Services Task Force. Screening for prostate cancer: Recommendation and rationale. Ann Intern Med 2002 Dec 3; 137:915-6.

• Original article (Subscription may be required)
• Medline abstract (Free)

Harris R and Lohr KN. Screening for prostate cancer: An update of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med 2002 Dec 3; 137:917-29.

• Original article (Subscription may be required)
• Medline abstract (Free)