Screening men beginning at age 50 for prostate cancer with a PSA blood test (Prostate Specific Antigen) and a digital rectal exam is recommended by the American Cancer Society, however the US Preventive Services Task Force found insufficient evidence to recommend screening. Identification or suspicion of prostate cancer can result in many procedures that have significant side effects, the most common serious adverse effects being impotence and incontinence. The PSA test produces many false positive results and consequent follow-up prostate biopsies that may be unnecessary. Prostate cancer is usually extremely slow in its development, and many men die of other causes before the prostate cancer has spread or caused significant illness.
Screening for prostate cancer has resulted in an increase in the risk that an American male will have to deal with prostate cancer from about 10 percent to 18 percent. Regular PSA tests will double the risk of a man having to go through the procedures to investigate whether cancer is present. Aggressive surgical treatment of prostate cancer, with its inevitable adverse effects, has only a modest benefit on mortality. In order for a screening test to prove valuable, the medical profession usually looks to the advantage shown through clinical studies. For example, many studies were conducted on mammography screening for breast cancer before it was accepted. By contrast, PSA screening tests have been adopted without any evidence showing their value. This is disconcerting, especially in light of a recent study that showed no benefit.
A study published in the January 9, 2006 issue of the Archives of Internal Medicine examined the association between prostate screening and deaths from prostate cancer. The study population was 71,661 patients treated at 10 Veterans Affairs medical centers. A total of 501 men were identified who had no diagnosis of prostate cancer before 1991, who were then diagnosed with prostate cancer between 1991-1995 and died between 1991-1999. The researchers then looked at whether these men had a previous screening PSA test or digital rectal exam prior to their diagnosis. Results of the study showed no difference in death rate in the group that had prior screening and the group that did not. Screening for prostate cancer was not associated with less deaths (Concato, 2006).
Two large clinical trials are underway to evaluate the effectiveness of PSA screening on mortality, one in the United States and one in Europe. The results of those studies will be published in 2009. Perhaps we should wait until then to rush out for more PSA screening tests or order them for our patients. The authors of the current study recommend that “the uncertainty of screening should be explained to patients in a process of ‘verbal informed consent,’ promoting informed decision making.”
Concato J, et al. The effectiveness of screening for prostate cancer: A nested case-control study. Archives of Internal Medicine 2006 (Jan 9); 166:38-43.