It has been shown by immunofluorometric and immunohistochemical assays that prostate-specific antigen (PSA) which is widely utilized for the diagnosis and management of prostate cancer, is not specific for the prostate gland itself but it also exists in breast, ovarian, endometrial, kidney, adrenal and salivary gland cancer tissues (Diamandis and Yu, 1997). This evidence concerns the gene KLK3 and prostate cancer.