PSA screening may be biased against obese men, leading to more aggressi...( DURHAM N.C. -- Testing men for eleva...),Health

DURHAM, N.C. -- Testing men for elevated levels of prostate-specific antigen (PSA) in the blood -- the gold standard screening test for prostate cancer -- may be biased against obese men, whose PSA levels tend to be deceptively low. And this bias may be creating more aggressive cancers in this population by delaying diagnosis, according to a new study led by investigators in the Duke Prostate Center and the Durham Veterans Affairs (VA) Medical Center.

"We know that obese men tend to have lower PSA values than their normal-weight counterparts, possibly caused by larger blood volumes which dilute the readings," said Stephen Freedland, M.D., a urologist at Duke and the Durham VA, and lead investigator on this study. "Now we know some of the real implications of this -- that these men are at a disadvantage in terms of prognosis compared to normal-weight men."

The researchers published their findings online in the journal BJU International. The study was funded by the United States Department of Veterans Affairs, the National Institutes of Health, the Georgia Cancer Coalition, the United States Department of Defense, the Prostate Cancer Research Program and the American Urological Association Foundation's Astellas Rising Star in Urology Award, given to Freedland.

"We used patient data to examine the association between body mass index, or BMI -- a measure of obesity -- and the amount of disease discovered after surgery to remove the prostate, " Freedland said. "We compared men who had their cancers detected by PSA screening to those who had an abnormal digital rectal exam, which may not confer the same bias against obese men."

The researchers looked at a total of nearly 3,400 men in the years since 2000, when PSA screening became the gold standard test for prostate cancer.

Obese patients whose cancer was diagnosed by PSA testing had more than twice the risk of cancer recurrence after surgery than their normal-weight cou
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