In a double-blinded, randomized, placebo-controlled multicenter trial, SFN has shown to significantly reduce levels of prostate-specific antigen (PSA) (44.4% SFN group vs. 71.8% in placebo), an antigen that is commonly elevated in prostate cancer after radical prostatectomy and used as a partial biomarker for “biochemical recurrence”. This evidence concerns the gene KLK3 and prostate carcinoma.