Digging Deeper into Prostate Screening Study

You may have read news coverage today about a Swedish study that found screening men ages 50 to 65 for prostate cancer can cut death rates from the disease by half. So how could this study stand in such stark contrast to other, larger studies that found much smaller (if any) mortality benefits? We asked Otis W. Brawley, M.D., the American Cancer Society’s chief medical officer to take a closer look. He brought up some issues that could help explain the finding.

“This is certainly an interesting study, and men need to consider it among the other evidence available when deciding whether to be screened for prostate cancer.

“As the accompanying editorial states, the findings show that in certain circumstances, PSA testing and early diagnosis reduces death from prostate cancer, but one cannot conclude from this study that PSA screening programs should now be introduced.

“It is important to recognize that this was not only a trial of screening alone; it was a trial of screening and superior treatment. Men in the screening group received treatment at a few centers that specialized in treatment of prostate cancer. The men in the control group received standard care in their community. That is likely to account for some and possibly all of the survival benefit.

“Most of the men in this trial were also included in a large European trial last year that showed only about half of the reduction in the risk of death, further pointing to the possibility treatment made the difference in this group.

“As in other studies, this trial had the difficulty that large numbers of men were diagnosed and treated that in retrospect did not require treatment.
Early signs of prostate cancer are so common in older men, what we need is a way to know which men with prostate cancer need treatment, and which ones have cancers that would not pose a problem.

“This and other studies have consistently shown the need for a validated test to determine the prostate cancers that when diagnosed should be observed as they are of no risk to the patients versus those that should be aggressively treated as they are a risk to the patient’s health.
The American Cancer Society and other leading organizations recommend that men be informed of and understand the complexities of screening, including learning the known risks and the potential for benefit before they undertake screening. Men really should have a good conversation with a physician who understands the issues and then make a decision for themselves about screening.”

Then one of our medical editors noticed something else: the risk of death from any cause, i.e. overall mortality, was the same in the screened group and the control group. Dr. Brawley pointed out that of the now four studies to date that report overall mortality among men screened for prostate cancer, three show mortality is actually a bit higher in the screened group.

To read more about prostate cancer screening, see the comprehensive section on our (new and improved!) web site.

About David Sampson

I am the director of medical and scientific communications for the American Cancer Society national home office.
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