Changes to This Summary (06/06/2013)
The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.
This section was extensively revised.
Added text to state that epidemiological studies have demonstrated that populations with high intake of dietary lycopene have lower risks of prostate cancer; prospective and case control studies have shown lycopene to be significantly lower in the serum and tissue of patients with cancer than in controls, while other studies have failed to demonstrate such a connection (cited Kristal et al. as reference 22).
Added text about a prospective cohort study of the association between lycopene serum concentration and risk of cancer that found men with the highest levels of serum lycopene had a 45% lower risk of cancer than did men with the lowest levels of lycopene.
Added text about a 2004 meta-analysis that investigated tomato intake and prostate cancer risk and reported that the relative risk of prostate cancer was 0.89 in men who consumed high amounts of raw tomato products and 0.81 in men who consumed the most cooked tomato products, compared with men who ate the least amount of raw tomatoes.
Revised text to state that the National Cancer Institute's Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial is an ongoing, prospective study that has been a source of subjects for investigations of an association between lycopene intake and prostate cancer risk; PLCO participants were followed for an average of 4.2 years.
Added text to state that variability in these epidemiological study results may be related to lycopene source; exposure misclassification; lack of a dose response; and confounding lifestyle factors, such as obesity, use of tobacco and alcohol, other dietary differences, varying standardization of quantities and compositions of lycopene, geographical location, and genetic risk factors.
Added text about a phase II, randomized, placebo-controlled trial of 45 men with clinically localized prostate cancer who received either lycopene or no supplement that suggested that other mechanisms mediated by steroid hormones may also be involved in the antioxidant properties of lycopene (cited Kumar et al. as reference 33).
Revised text to state that in one 2011 study that explored the effects of lycopene and fish oil supplements on gene expression, men with low-risk prostate cancer were randomly assigned to receive lycopene, fish oil, or a placebo daily for 90 days.
Added text to state that a 2006 study reported the median prostate-specific antigen doubling time increased from 11.5 months to 28.7 months after 33 months of follow-up.
Added text about a phase II, randomized, double-blinded, placebo-controlled trial of men with localized prostate cancer who received either isoflavones or placebo that concluded that increasing concentrations of plasma isoflavones daidzein and genistein in the isoflavone-treated group was inversely correlated with changes in serum prostate-specific antigen, compared with the placebo arm (cited 2007 Kumar et al. [Nutrition and Cancer, pp 163-8] as reference 30 and 2007 Kumar et al. [Nutrition and Cancer, pp 169-75] as reference 31).
Added text about a phase II, multidose, randomized placebo-controlled trial of 45 men with localized prostate cancer who received either a purified isoflavone supplement or no supplement that concluded that 40 mg of isoflavones may be the best dose to use in a future definitive, larger phase II clinical trial to evaluate purified isoflavones in prostate carcinogenesis.
This summary is written and maintained by the PDQ Cancer Complementary and Alternative Medicine Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ Editorial Boards in maintaining the PDQ summaries can be found on the About This PDQ Summary and PDQ NCI's Comprehensive Cancer Database pages.