Previous cancer therapies, low PSMA expression caused by tumor heterogeneity, or PCa lesions containing only small amounts of cancer cells might be responsible for false-negative 18F-PSMA PET/CT results in some PCa patients; false negative findings may be also due to PCa lesions located in sites of physiological radiopharmaceutical uptake [24,25,26,27,28,29,30,31]. The gene discussed is FOLH1; the disease is cancer.