Increasing evidence suggests that
lycopene, a major
carotenoid detected in human plasma, may be preventive against the formation and the development of different types of human
cancers including prostate, breast, and
lung cancer. Experimental studies demonstrated that
lycopene inhibits the growth of various
cancer cells of different organs and prevent chemically induced
carcinogenesis in animal models. Although the excellent
antioxidant property of
lycopene is most likely the basis for its preventive role toward
cancer, the direct anticancer activities of
lycopene through multiple mechanisms are disclosed, including regulation of
growth factor signaling, cell cycle arrest and/or apoptosis induction, and changes in
antioxidant and phase II detoxifying
enzymes. The anti-inflammatory activity of
lycopene is also considered as an important determinant that suppresses the promotion and progression of
carcinogenesis. Moreover,
lycopene inhibits cell invasion, angiogenesis, and
metastasis. Importantly, those activities have been shown to be exhibited at the physiologically attainable concentration in humans. Although the preclinical data strongly suggest an antitumor activity of
lycopene, a number of epidemiological and intervention studies indicate that there is still no clear clinical evidence that supports its use for the prevention of those
cancers. More well controlled clinical intervention trials are needed to further clarify the exact role of
lycopene in the
cancer prevention. Nonetheless, because of its multiple
tumor-inhibitory activities,
lycopene still remains to be an attractive and promising
carotenoid that will potentially contribute to the prevention and treatment of human
cancers. This chapter reviews data on the
cancer preventive activities of
lycopene, possible mechanisms involved, and the relationship between
lycopene consumption and human
cancer risk.