Obese Men With Prostate Cancer Generally Have Lower PSA Levels

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Main Category: Prostate / Prostate Cancer
Also Included In: Obesity / Weight Loss / Fitness;  Urology / Nephrology;  Men's health
Article Date: 20 Nov 2007 - 13:00 PDT

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Obese men with prostate cancer are more likely to have lower PSA levels than non-obese men with prostate cancer - a higher body mass index (BMI) is linked to higher plasma volume, which in turn can lead to lower PSA (prostate-specific antigen) levels, according to an article published in The Journal of the American Medical Association (JAMA), November 21 issue.

The authors explain that recent evidence indicates that prostate cancer screening may be adversely affected by a higher BMI. Prostate cancer detection accuracy can be compromised if PSA concentration in the blood is lower because of obesity, or other factors. Several studies found that obese men tend to have lower PSA concentrations, compared to men who are not obese.

The researchers say "However, men with higher BMIs also have larger plasma volumes, which could decrease serum concentrations of soluble tumor markers - a phenomenon known as hemodilution."

Lionel L. Bañez, M.D., Duke University Medical Center, Durham, N.C., and team carried out a study to find out what the link between hemodilution and PSA concentration in obese men with prostate cancer was. The study looked at men who had undergone radical prostatectomy for prostate cancer during the period 1988-2006. 1,373 had been treated at the Shared Equal Access Regional Cancer Hospital, 1,974 at the Duke Prostate Center, and 10,287 at Johns Hopkins Hospital.

The scientists found that there was a significant link between higher BMI and greater plasma volume in all study populations. A man whose BMI is at least 35 has 21%-23% higher plasma volumes compared to a man of normal weight, the authors wrote. After making adjustments for multiple clinicopathological variables, higher BMI was linked to lower pre-operative PSA concentrations in the groups. Men whose BMIs were at least 35 had 11%-21% lower PSA concentrations compared to a normal weight man.

The researchers concluded "In 3 distinct prostate cancer cohorts, all treated by radical prostatectomy, hemodilution from increased plasma volume may be responsible for the observed decreased PSA concentration in men with higher BMI. This association needs to be confirmed prospectively in screened populations that include men without prostate cancer."

JAMA
2007;298(19):2275-2280

Written by - Christian Nordqvist
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