Prostate test may be biased against obese

DURHAM, N.C., Aug. 11 (UPI) -- Testing men for prostate-specific antigen, or PSA, in the blood may be biased against obese men, U.S. researchers say.

Investigators at the Duke University Prostate Center and the Durham Veterans Affairs Medical Center say obese men may have PSA levels that tend to be deceptively low. That tendency may mean more aggressive cancers have a greater chance of spreading because diagnosis is delayed, they say.

"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," study leader Stephen Freedland, a urologist at Duke, said in a statement. "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."

Freedland looked at patient data of nearly 3,400 men to examine the association between body mass index and the amount of disease discovered after surgery to remove the prostate.

Obese patients whose cancer was diagnosed by PSA testing had more than twice the risk of cancer recurrence after surgery than their normal-weight counterparts, Freedland said.

The findings were published in the journal BJU International.