Additionally, 11C- or 18F-choline are designed to target tumor cells directly (31), and the European Association of Urology (EAU) once suggested referring patients for 11C- or 18F-choline PET/CT when the prostate-specific antigen (PSA) increases >1 ng/ml, and the result is expected to change patient management (32). Here, KLK3 is linked to neoplasm.