Lycopene in the treatment of prostate cancer

Abstract

Dietary intake of lycopene is associated with reduced risk of prostate cancer (PCa). We conducted a clinical trial in men with prostate cancer to investigate the biological and clinical effects of lycopene supplementation. Twenty-six men with prostate cancer were randomly assigned to receive a lycopene supplement or no supplement for three weeks before radical prostatectomy. Subjects in the intervention group (n = 15) were instructed to take a tomato oleoresin extract soft gel capsule (Lyc-O-Mato®, LycoRed Company, Beer Sheva, Israel) containing 15 mg lycopene, 1.5 mg phytoene, 1.5 mg phytofluene, and 5 mg tocopherol twice daily with meals. Prostatectomy specimens were evaluated for pathologic stage, Gleason score, volume of cancer, and extent of high-grade prostatic intraepithelial neoplasia (HGPIN). Biomarkers of cell proliferation and apoptosis were assessed by Western blot analysis in benign and cancerous tissue samples obtained from the prostatectomy specimens. Oxidative stress was assessed by measuring the peripheral blood lymphocyte DNA oxidation product 5-hydroxymethyl-deoxyuridine (5-OH-mdU). Plasma levels of lycopene, insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), and prostate-specific antigen (PSA) were measured at baseline and after three weeks of study period. After the intervention, more men in the intervention group had smaller (<4 cc) tumors, organ-confined disease without involvement of surgical margins or extra-prostatic tissues, and focal involvement of the prostate with HGPIN compared to the control group. Mean plasma PSA levels were lower in the intervention group compared to the control group. This pilot study suggests that a tomato extract containing lycopene and other tomato carotenoids and phytochemicals may have a potential role in the treatment of prostate cancer. Larger clinical trials are necessary to definitively address potential uses of lycopene or tomato extract in the prevention or treatment of prostate cancer.