Foible No. 1. PSA is made exclusively by prostate epithelial cells, and
the serum level of PSA is dependent (at least in part) on the number of these
cells present. Some prostate glands are much richer in epithelium than others.
The epithelial content of different prostate glands has been shown to range
from a low of 12% to a high of 31%, average of 19%, in men whose whole prostate
was studied. Prostates rich in epithelium are associated with higher serum
levels of PSA than glands which are poor in epithelium. Thus, Foible 1 is that
PSA varies with the epithelial content of the gland, something which has no
direct relationship to prostate cancer.