KLK3 and prostate cancer: Follow-up studies conducted by health professionals found that lycopene intake was associated with a decreased risk of prostate cancer, including lethal prostate cancer.8,9 Three studies have suggested a null association between dietary lycopene intake and prostate cancer risk.11,12,15 In serum lycopene levels, two studies suggested a protective effect for prostate cancer,31,32 and three studies supported no association.33–35 The seemingly positive association between localized prostate cancer risk and lycopene intake could be explained by confounding related to PSA screening.