Prostate cancer is the most common cancer affecting American men and ranks second in mortality. According to the study, screening tests almost always increase the detection of cancer, but among other requirements for improving survival, the tumors detected must be both fatal (if left untreated) yet curable.
PSA, a protein produced in the prostate, is found in the blood of healthy men. Prostate cancer often increases PSA levels in the blood, but a similar increase can be caused by benign enlargement of the prostate gland (prostatism) or prostate infections.
To test the impact of prostate cancer screening on survival, the researchers conducted a case-control review of the medical records of over 1,000 male veterans age 50 or older receiving care at 10 VA medical centers in New England. Half of the men had died with prostate cancer; the other half were living and matched to be the same age as those who died. The study included up to nine years of follow-up after the diagnosis of cancer. The researchers compared the group that died to the group that lived and found that the same fraction of men had received screening with the PSA test.
"This study suggests that screening was not effective," said first author John Concato, M.D., associate professor of medicine at Yale School of Medicine and director of the Clinical Epidemiology Research Center at the VA Connecticut Healthcare System. "If screening worked, men who died would have had less testing than those who lived."
Concato and his team also determined that digital rectal examinations along with PSA did not improve survival.
"Unfortunately, screening tests can sometimes find cancer, even at early stages, but not prolong survival," said Concato, who is also a member of the Yale Cancer Center. "Rather than encouraging annual screening of all men starting at age 50, as is commonly done, the limited effectiveness of PSA testing should be explained to patients in the process of obtaining their informed consent to the test."
The study was supported by funding from the Department of Veterans Affairs.
Other authors on the study included Carolyn K. Wells, Ralph I. Horwitz, M.D., David Penson, M.D., Graeme Fincke, M.D., Dan R. Berlowitz, M.D., Gregory Froehlich, M.D., Dawna Blake, M.D., Martyn A. Vickers, M.D., Gerald A. Gehr, M.D., Nabil H. Raheb, M.D., and Peter Peduzzi.
Citation: Archives of Internal Medicine, Vol. 166 (January 9, 2006)