Dec. 3, 2002 -- Men looking for a simple answer to their questions about prostate cancer screening will find little solace in the findings of a major government task force. After reviewing recent research on the issue, the group says there is not enough evidence to make a recommendation for or against routine prostate cancer screening.
Prostate cancer is the most common cancer among men and the second leading cause of cancer death among men, following lung cancer. According to the American Cancer Society (ACS), 189,000 men will be diagnosed with prostate cancer in the U.S. this year, and more than 30,000 men will die of the disease.
Death rates from prostate cancer have dropped since the use of prostate cancer screening tests, such as the PSA blood test and rectal exam, became common in the 1990s, according to the ACS. However, there is no direct evidence that this drop is a result of screening tests.
The results of the U.S. Preventive Services Task Force report appear in the Dec. 3 issue of the Annals of Internal Medicine.
Researchers say one of the biggest problems in evaluating the effectiveness of prostate cancer screening is that the severity of the tumors varies greatly, and the screening tests aren't very specific.
Many of these tumors grow very slowly and may not ever cause a problem for many of the men diagnosed with the disease. But current screening methods can only distinguish a small number of men with either the best or worst chances for survival. They aren't very good at making predictions about the survival chances for men who fall in the middle, which accounts for the vast majority of prostate cancer cases.
Although there are virtually no health risks associated with the screening tests themselves, experts say the risks associated with widespread prostate cancer screening lie in the uncertainties about the disease itself, how to interpret test results, and making treatment decisions.
Durado Brooks, MD, MPH, director of prostate cancer at ACS, says men need to understand that the PSA test, which measures the level of a protein produced by normal prostate cells as well as prostate cancer cells, still misses about 10% to 15% of cancers.
Even if PSA levels are found to be higher than normal, Brooks says it is very often due to something other than cancer, such as benign prostate enlargement. Even so, he says those results may still cause unnecessary anxiety for many men.
"Once you do a prostate cancer screening, decisions have to be made about treatments that can have some very untoward side effects," says Brooks.
"So, when you go back to fact that some men have prostate cancers that will never cause them any harm and now you offer treatments that have unpleasant side effects, men need to understand that going in," says Brooks. "Men should talk about the benefits and limitations and understand the pros and cons to make an informed decision."
Brooks says the report's findings now put the task force largely in line with the recommendations of other major medical organizations, including the American Cancer Society (ACS) and the American Urological Association. The last time the task force looked at prostate cancer screening in 1996, it recommended against it.
Those organizations and others currently recommend that doctors offer annual prostate cancer screening to men over 50 and discuss the potential risks and benefits.
"Men with a life expectancy of fewer than 10 years are unlikely to benefit from screening even under favorable assumptions," write the authors of the report, Russell Harris, MD, MPH, and Kathleen N. Lohr, PhD, of the University of North Carolina at Chapel Hill and Research Triangle Institute.
Although not endorsed by the report, ACS also recommends annual screening for men over age 45 who are at high risk for prostate cancer -- African-Americans or men with a brother or father who had prostate cancer.
While there is some indication that some dietary factors may affect the risk of developing prostate cancer, Brooks says those claims have not yet been proven and several studies are currently investigating new prevention strategies for prostate cancer.