A US study of 13,634 men undergoing radical prostatectomy at three US hospitals, found men with a Body Mass Index of 35 or greater had 11%-21% lower prostate specific antigen concentrations compared with normal-weight men.
It also found that higher BMI was associated with a higher plasma volume, although the mass of prostate specific antigen in the body did not change.
Authors said that larger plasma volumes in obese men could dilute the amount of prostate specific antigen in the bloodstream.
They said: 'Haemodilution 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: 2267-2274