KLK3 and posterior cortical atrophy: Although no control group is perfect, one might select controls for a serum based study of PCa as being males with PSA ≤ 10 ng/ml, a normal digital rectal examination, normal prostatic ultrasonography, and a recent negative biopsy (at least sextant) of the prostate taken after the sample of serum was obtained because biopsy of the prostate may “activate” the prostate for several weeks subsequently (Urban et al, 1999).