KLK3 and cancer: Cancer detection evolved from Celsus in 28 B.C. [1], benign-malignant distinction (eighteenth century) [2], carcinoma-sarcoma classification (1838) [3], the Pap smear (1930) [4], mammography (1950s) [5], to tumor markers like carcinoembryonic antigen (CEA) [6], and prostate-specific antigen (PSA) in 1965–1970 [7] providing new tools for cancer detection and monitoring.