Dilution from increased plasma volumes may be the reason for lower levels
of prostate-specific antigen (PSA) observed in groups of obese men with
prostate cancer. Researchers report in the November 21, 2007 issue of
the Journal of the American Medical association that men in the most obese
group have PSA concentrations between 11% to 21% lower than seen in men
of normal weight.
One result of lower PSA levels in obese men may be delay in detection at
an early stage when the disease might be more amenable to treatment. It
is known that obese men have more aggressive cancers but how much of that
is explained by a later diagnosis has not been established.
American Cancer Society statistics dating back to the 1960, showed that
obese men had worse outcomes so it’s not purely an issue of delayed
diagnosis, but it does contribute.
Researchers stated that hemodilution from increased plasma volume might
be the cause for the lower PSA concentration seen in obese patients.
Another conclusion was that it might be prudent to lower the threshold
in screening of obese men for an abnormal result.