New Ultrasensitive Assays Facilitate Studies on the Role of Human Glandular Kallikrein (hK2) as a Marker for Prostatic Disease

Prostate cancer is the most common non-skin cancer in men, and it is an important cause of morbidity and mortality. The growth rate of prostate cancer is unusually slow. It has been estimated that the tumor starts develop-ing at 20–30 years of age and reaches a detectable stage 30–40 years later (1). This estimate is based on the doubling time of the serum concentrations of prostate-specific antigen (PSA),;2 years (2), and the prevalence of high-grade prostatic intraepithelial neoplasia and micro-scopic cancers in prostates removed at autopsy (3, 4) in various age groups. Studies on archival serum samples from men who later developed prostate cancer have shown that the serum concentrations of PSA begin in-creasing 5–10 years before clinical presentation (2, 5). When serum PSA exceeds the commonly used cutoff (