It is well known that certain clinical factors, such as PSA levels, PSA kinetics (eg, PSA doubling time [PSAdt]), and Gleason scores, can influence the diagnostic performance of some PET radiopharmaceuticals, including 11C- or 18F-choline and 18F-fluciclovine.11, 12, 13, 14 This is likely because higher baseline PSA and Gleason scores and shorter PSAdt are a reflection of disease aggressiveness and burden and have been recognized as independent prognostic factors for prostate cancer.15 The gene discussed is KLK3; the disease is prostate carcinoma.