Janssen et al. [23], in 2017, conducted a study that included 54 prostate cancer patients with a mean prostate-specific antigen (PSA) level of 38.4 ± 77.9 ng/mL and mean age of 69.6 ± 6.5 years, while Simsek et al. [30], in 2020, enrolled 138 prostate cancer patients with a median PSA level of 18.3 ng/mL and mean population age of 66 years, with the same purpose, to compare the diagnostic abilities of bone SPECT-CT and 68Gallium-prostate specific membrane antigen ([68Ga]-PSMA) PET-CT in metastatic bone lesion identification and staging. The gene discussed is KLK3; the disease is prostate cancer.