Background: Lycopene has been promoted for prostate cancer prevention, despite the inconsistency of scientific evidence. Methods: This nested case-control study examined whether serum lycopene was associated with prostate cancer risk among participants in the Prostate Cancer Prevention Trial, a placebo-controlled trial of finasteride for prostate cancer prevention. Presence or absence of cancer was determined by prostate biopsy, recommended during the trial due to elevated prostate specific antigen (PSA) level or abnormal digital rectal examination (DRE) and offered to all men at the trial end. There were 1,683 cases (461 Gleason score ≥ 7, 125 Gleason score ≥ 8) and 1,751 controls. Results: There were no associations of lycopene with prostate cancer risk. The odds ratios for a linear increase in lycopene (per 10 mg/dL) were 0.99 (95% CI: 0.94-1.04), 1.01 (0.94-1.08), and 1.02 (0.90-1.15) for Gleason 2 to 6, 7 to 10, and 8 to 10, respectively. In the placebo arm, a 10 mg/dL increase in lycopene was associated with a 7% (95% CI: 14-0) reduced risk of cancer diagnosed following an elevated PSA or abnormal DRE, which are cancers that best match those detected in screened populations. However, a 10 mg/dL increase in lycopene was also associated with an 8% (95% CI: 1-16) increased risk of cancer diagnosed without a biopsy prompt, which are cancers generally not detected. These findings were similar for low- and high-grade cancer. Conclusion: This study does not support a role for lycopene in prostate cancer prevention. Impact: Scientists and the public should understand that early studies supporting an association of dietary lycopene with reduced prostate cancer risk have not been replicated in studies using serum biomarkers of lycopene intake. Recommendations of professional societies to the public should be modified to reflect the likelihood that increasing lycopene intake will not affect prostate cancer risk.
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