At 4 ng/mL (upper limit of the reference interval) PSA fails to detect a substantial number of cancers, and the Prostate Cancer Prevention Trial has concluded that there is no cutoff value for PSA level with simultaneous high sensitivity and high specificity for monitoring healthy men for PCA but rather a continuum of prostate cancer risk at all values of PSA [11]. The gene discussed is KLK3; the disease is prostate carcinoma.