Prostate Cancer: To Screen or Not to Screen?

"Because many prostate cancers grow slowly, early detection may not benefit a patient's health and in some cases may even cause harm," said Ned Calonge, M.D., M.P.H., USPSTF chair and chief medical officer for the Colorado Department of Public Health and Environment. According to the Agency for Healthcare Quality and Research, which convened the panel, one-third of all men in the United States over 75 are receiving PSA testing.

The guidelines update 2002 recommendations that said there was insufficient evidence to make recommendations about PSA screening and digital rectal exams for men of any age. Yet one in 6 men of all ages now receives a prostate cancer diagnosis. However, the new guidelines cite statistics that suggest many men are over-diagnosed, based on screening. Prostate cancer is not always a rapidly growing or dangerous form of cancer. In some cases, it progresses so slowly that it may not even be detected during a man’s life if screening is not done. The panel cites a 2002 study indicating that 29% to 44% of men who are diagnosed with cancer based on PSA tests would have this slow-growing kind of cancer and would receive unnecessary treatment.

For men over 75—or with a life expectancy less than 10 years—the potential harms associated with screening outweigh the benefits of detecting prostate cancer early according to the recommendations. The panel says harm from screening can include the discomfort of biopsy, and possible false positive results and resulting psychological distress. Prostate cancer treatment can cause erectile dysfunction, incontinence, and death.

For men under 75, the panel said it did not find enough medical evidence to balance the harms and benefits of screening. USPSTF urged physicians and patients to discuss the “uncertain benefits and the known harms of prostate cancer screening and treatment” with patients before ordering tests.

USPSTF recommendations are at odds with those from other groups concerned with prostate cancer. Both the American Urological Association and the American Cancer Society recommend offering screening at age 50 to men with a life expectancy of 10 years. Some guidelines urge earlier screening for high-risk men, including African Americans and those with a strong family history of prostate cancer. The National Comprehensive Cancer Network suggests that screening begin at age 40.

A recent editorial by a prominent prostate cancer researcher who favors PSA testing cites studies that show sharp drops in advanced prostate cancer rates and deaths since the advent of PSA screening. Writing in The Washington Post, William J. Catalona, MD of Northwestern University also points to studies that suggest 45 % to 70% of the decline in prostate cancer rates and deaths is due to PSA screening. “If screening detected only harmless cancers, treating them could not produce the striking decline in prostate cancer rates that has occurred,” he writes. Catalona adds that the USPSTF recommendation and related media coverage “could give reluctant men an excuse to postpone or forgo screening. The consequence might be that many men die of prostate cancer unnecessarily.”

Because of these conflicting recommendations, men should discuss prostate cancer screening with their doctor regarding the benefits and risks of screening based on their current health status.

Sources

United State Preventive Screening Task Force. Screening for Prostate Cancer: U.S. Preventive Services Task Force Recommendation Statement. Ann Intern. Med 2008; 149: 185-191.

Screening for Prostate Cancer: Clinical Summary of U.S. Preventive Services Task Force Recommendation. Agency for Healthcare Research and Quality. Available online through http://www.ahrq.gov. Issued August 2007. Accessed August 27, 2008.

Agency for Healthcare Research and Policy. Task Force Says Men Age 75 and Older Should Not Be Screened for Prostate Cancer. Available online at http://www.ahrq.gov/news/press/pr2008/tfproscanpr.htm. Issued August 4, 2008. Accessed August 27, 2008.

Catalona, W. The Wrong Call on Prostate Cancer Screening. The Washington Post. August 26, 2008.