In detail, supplementation of cholecalciferol (ranging from 400 to 40,000 IU/die) for a period of one month in prostate cancer patients is associated with modest prostate specific antigen (PSA) and PTH reduction before prostatectomy although circulating and prostate tissue levels of 25(OH)D and 24,25(OH)2D significantly increased in supplemented patients from baseline as well as circulating and prostate tissue levels of 25(OH)D were significantly higher in 40,000 IU/die treated group [115]. The gene discussed is KLK3; the disease is prostate carcinoma.