Dietary Lycopene Protects Against Advanced Prostate Cancer

Research indicates that dietary lycopene’s role in prostate cancer prevention may be in reducing tumours’ angiogenic potential

medwireNews: Men with a high intake of dietary lycopene have a reduced risk of developing lethal prostate cancer, say researchers.

The team, led by Edward Giovannucci, from Harvard School of Public Health in Boston, Massachusetts, USA, studied several tumour biomarkers and found that men in the fifth quintile for lycopene intake (10,131–115,012 µg/day) had tumours with a lower angiogenic score and vessels that were larger and less irregular, and therefore had less angiogenic potential, than those of men in the first quintile for lycopene intake (0–3687 µg/day).

“Lycopene may inhibit angiogenesis of prostate cancer cells by regulating Vascular endothelial growth factor,” suggest the researchers in the Journal of the National Cancer Institute.

Given that angiogenesis is a strong risk factor of progression, the researchers suggest that advanced or lethal prostate cancer may be a better endpoint than total prostate cancer for studying the potential benefits of dietary lycopene in prostate cancer prevention.

They studied dietary information on 47,898 men. The 9,626 men in the highest quintile for lycopene intake were a significant 9% less likely to develop prostate cancer and 28% less likely to develop lethal prostate cancer than the 9,470 men in the lowest quintile.

When only men with at least one negative prostate-specific Antigen (PSA) test were considered, the association between lycopene intake and the risk of lethal prostate cancer became much stronger, with the risk reduced by 53% for those in the highest versus lowest quintile. The association was also much stronger in men who had had high intakes of lycopene over a longer period of time, which suggests “that lycopene may be acting early in the disease process”, says the team.

Edward Giovannucci and colleagues note that there has been much controversy over the role of lycopene and tomato-based products - the primary source of dietary lycopene - in prostate cancer prevention. They believe that factors contributing to this include imprecise measurement of lycopene bioavailability, single rather than repeated measurement of the antioxidant, variation in lycopene intake across populations, and the fact that the endpoint has been indolent rather than lethal prostate cancer.

“In the setting of widespread PSA screening, advanced or lethal prostate cancer is preferable to total prostate cancer as the endpoint for epidemiological studies of lycopene,” they conclude.

Reference

Zu K, Mucci L, Rosner B, et al. Dietary lycopene, angiogensis, and prostate cancer: A prospective study in the prostate-specific antigen era. J Natl Cancer Inst; Advance online publication January 24, 2014. doi: 10.1093/jnci/djt430.

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