Obese men, unwitting victims of aggressive cancers

August 8th, 2008 - 5:09 pm ICT by IANS  

Washington, Aug 8 (IANS) Testing for elevated levels of prostate-specific antigen may be biased against obese men whose PSA levels tend to be deceptively low. This bias may be creating more aggressive cancers in this population by delaying diagnosis, according to a new study led by Duke Prostate Centre and Durham Veterans Affairs (VA) Medical Center investigators.

“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, 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.”

“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 counterparts, Freedland said. “In contrast, obese men with abnormal digital rectal exams had similar outcomes as normal-weight men,” Freedland said.

Another Duke study provides further substantiation of the concern that obese men have poorer prognoses than normal-weight men. This suggests that prostate cancer surgery is technically more challenging in obese men, making complete tumour removal harder, according to Jayakrishnan Jayachandran of Duke and lead investigator on the second study.

These findings were published online in BJU International.

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