“Dietary intake of lycopene was associated with reduced risk of lethal prostate cancer and with a lesser degree of angiogenesis in the tumor,” Ke Zu, MD, of Harvard School of Public Health, Boston, and colleagues concluded after reviewing dietary information and total and lethal prostate cancer cases among 49,898 male health professionals. “Because angiogenesis is a strong progression factor, an endpoint of lethal prostate cancer may be more relevant than an endpoint of indolent prostate cancer for lycopene in the era of highly prevalent prostate-specific antigen screening,” the investigators wrote in the Journal of the National Cancer Institute.
“Higher lycopene intake was inversely associated with total prostate cancer and more strongly with lethal prostate cancer (top vs bottom quintile: [hazard ratio (HR)] = 0.72; 95% CI = 0.56 to 0.94; P trend = .04),” the researchers reported. “In a restricted population of screened participants, the inverse associations became markedly stronger (for lethal prostate cancer: HR = 0.47; 95% CI = 0.29 to 0.75; P trend = .009). Comparing different measures of dietary lycopene, early intake, but not recent intake, was inversely associated with prostate cancer. Higher lycopene intake was associated with biomarkers in the cancer indicative of less angiogenic potential.”
The study participants were dentists, optometrists, podiatrists, pharmacists, and veterinarians who were between 40 and 75 years old at baseline in 1986. Dietary intake was assessed by questionnaires, and prostate cancer diagnoses were initially identified through reporting on questionnaires, then confirmed by a review of medical records and pathology reports.
“Participants in the upper quintiles of lycopene intake were slightly younger and more likely to engage in vigorous physical activity. Men who consumed more lycopene in their diet also consumed less alcohol, coffee, and all three types of fats and slightly more fruits, vegetables, and dietary fiber,” the authors observed.
“Lycopene, a carotenoid with multiple bioactivities, is found abundantly in tomato, tomato-based products, pink grapefruit, and watermelon,” the investigators noted. Some but not all previous studies had shown that dietary lycopene was associated with reduced risk of prostate cancer.
In the current study, investigators “evaluated tumor biomarkers for various cellular and molecular events in relation to lycopene intake and found that higher lycopene intake was associated with lower angiogenic potential in the tumor based on the vessel size and shape. Based on these results,” the investigators stated, “we hypothesize that the consumption of a diet rich in lycopene-containing foods reduces the aggressive potential of prostate cancer by inhibiting the neoangiogenesis that occurs in tumor development.” ■
Zu K, et al: J Natl Cancer Inst 106(2):djt430, 2014.