KLK3 and pachyonychia congenita: This cohort study evaluated whether a significant interaction existed between (1) a pre-RP PSA level greater than 20 ng/mL vs 20 ng/mL or less and (2) persistent PSA vs undetectable PSA after RP on PC-specific mortality (PCSM) risk and all-cause mortality (ACM) risk, adjusting for known PC prognostic factors, age at RP, year of RP, and the time-dependent use of post-RP radiation therapy (RT) and androgen deprivation therapy (ADT).